Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||||
IRequestCycle |
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| 1.0;1 |
1 | // Copyright 2004, 2005 The Apache Software Foundation |
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2 | // |
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3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
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4 | // you may not use this file except in compliance with the License. |
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5 | // You may obtain a copy of the License at |
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6 | // |
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7 | // http://www.apache.org/licenses/LICENSE-2.0 |
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8 | // |
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9 | // Unless required by applicable law or agreed to in writing, software |
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10 | // distributed under the License is distributed on an "AS IS" BASIS, |
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11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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12 | // See the License for the specific language governing permissions and |
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13 | // limitations under the License. |
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14 | ||
15 | package org.apache.tapestry; |
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16 | ||
17 | import org.apache.hivemind.ApplicationRuntimeException; |
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18 | import org.apache.tapestry.engine.IEngineService; |
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19 | import org.apache.tapestry.services.Infrastructure; |
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20 | import org.apache.tapestry.services.ResponseBuilder; |
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21 | ||
22 | import java.util.Iterator; |
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23 | ||
24 | /** |
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25 | * Controller object that manages a single request cycle. A request cycle is one 'hit' on the web |
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26 | * server. In the case of a Tapestry application, this will involve: |
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27 | * <ul> |
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28 | * <li>Responding to the URL by finding an {@link IEngineService}object |
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29 | * <li>Determining the result page |
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30 | * <li>Renderring the result page |
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31 | * <li>Releasing any resources |
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32 | * </ul> |
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33 | * <p> |
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34 | * Mixed in with this is: |
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35 | * <ul> |
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36 | * <li>Exception handling |
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37 | * <li>Loading of pages and templates from resources |
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38 | * <li>Tracking changes to page properties, and restoring pages to prior states |
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39 | * <li>Pooling of page objects |
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40 | * </ul> |
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41 | * |
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42 | * <p> |
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43 | * A request cycle is broken up into two phases. The <em>rewind</em> phase is optional, as it tied |
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44 | * to {@link org.apache.tapestry.form.Form} |
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45 | * components. In the rewind phase, a previous page render is redone (discarding output) until a |
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46 | * specific component of the page is reached. This rewinding ensures that the page is restored to |
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47 | * the exact state it had when the URL for the request cycle was generated, taking into account the |
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48 | * dynamic nature of the page ({@link org.apache.tapestry.components.ForBean}, |
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49 | * {@link org.apache.tapestry.components.Conditional}, etc.). Once this component is reached, it |
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50 | * can notify its {@link IActionListener}. The listener has the ability to update the state of any |
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51 | * pages and select a new result page. |
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52 | * </p> |
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53 | * |
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54 | * <p> |
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55 | * Following the rewind phase is the <em>render</em> phase. During the render phase, a page is |
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56 | * actually rendered and output sent to the client web browser. |
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57 | * </p> |
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58 | * @author Howard Lewis Ship |
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59 | */ |
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60 | ||
61 | public interface IRequestCycle |
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62 | { |
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63 | /** |
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64 | * Invoked after the request cycle is no longer needed, to release any resources it may have. |
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65 | * This includes releasing any loaded pages back to the page source. |
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66 | */ |
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67 | ||
68 | void cleanup(); |
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69 | ||
70 | /** |
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71 | * Passes the String through |
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72 | * {@link javax.servlet.http.HttpServletResponse#encodeURL(java.lang.String)}, which ensures |
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73 | * that the session id is encoded in the URL (if necessary). |
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74 | * |
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75 | * @param URL The url to encode. |
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76 | * @return The encoded form of the url. |
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77 | */ |
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78 | ||
79 | String encodeURL(String URL); |
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80 | ||
81 | /** |
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82 | * Returns the engine which is processing this request cycle. |
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83 | * |
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84 | * @return The engine. |
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85 | */ |
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86 | ||
87 | IEngine getEngine(); |
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88 | ||
89 | /** |
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90 | * Retrieves a previously stored attribute, returning null if not found. Attributes allow |
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91 | * components to locate each other; primarily they allow a wrapped component to locate a |
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92 | * component which wraps it. Attributes are cleared at the end of the render (or rewind). |
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93 | * |
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94 | * @param name The name of the attribute to retrieve. |
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95 | * @return The matching attribute with the specified name, or null if none found. |
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96 | */ |
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97 | ||
98 | Object getAttribute(String name); |
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99 | ||
100 | /** |
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101 | * Identifies the active page, the page which will ultimately render the response. |
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102 | * |
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103 | * @return The active page. |
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104 | */ |
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105 | ||
106 | IPage getPage(); |
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107 | ||
108 | /** |
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109 | * Returns the page with the given name. If the page has been previously loaded in the current |
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110 | * request cycle, that page is returned. Otherwise, the engine's page loader is used to load the |
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111 | * page. |
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112 | * |
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113 | * @param name The page to get a reference to. |
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114 | * @return The page instance. |
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115 | * |
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116 | * @throws PageNotFoundException |
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117 | * if the page does not exist. |
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118 | * |
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119 | * @see org.apache.tapestry.engine.IPageSource#getPage(IRequestCycle, String) |
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120 | */ |
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121 | ||
122 | IPage getPage(String name); |
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123 | ||
124 | /** |
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125 | * Returns true if the context is being used to rewind a prior state of the page. This is only |
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126 | * true when there is a target action id. |
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127 | * |
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128 | * @return True if rewinding a form, false otherwise. |
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129 | */ |
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130 | ||
131 | boolean isRewinding(); |
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132 | ||
133 | /** |
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134 | * Checks to see if the current action id matches the target action id. Returns true only if |
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135 | * they match. Returns false if there is no target action id (that is, during page rendering). |
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136 | * <p> |
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137 | * If theres a match on action id, then the component is compared against the target component. |
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138 | * If there's a mismatch then a {@link StaleLinkException}is thrown. |
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139 | * |
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140 | * @param component The component to check. |
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141 | * @return True if the specified component has been rewound. |
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142 | */ |
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143 | ||
144 | boolean isRewound(IComponent component); |
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145 | ||
146 | /** |
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147 | * Sets the {@link ResponseBuilder} to use for this response, don't |
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148 | * try setting this unless you're very sure you know what you are doing as |
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149 | * this isn't the only way that it is used. (ie replacing this builder won't |
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150 | * necessarily override another builder being used already) |
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151 | * |
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152 | * @param builder The response builder that may be used by components |
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153 | * to help with delegate/sub component rendering. |
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154 | */ |
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155 | void setResponseBuilder(ResponseBuilder builder); |
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156 | ||
157 | /** |
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158 | * Entry point for getting the response builder used to build |
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159 | * this response. |
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160 | * @return The response builder used for this response. |
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161 | */ |
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162 | ResponseBuilder getResponseBuilder(); |
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163 | ||
164 | /** |
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165 | * Tests if the render component chain is empty, meaning no components have |
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166 | * been loaded onto the stack yet. |
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167 | * |
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168 | * @return True, if the current stack is empty. |
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169 | */ |
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170 | boolean renderStackEmpty(); |
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171 | ||
172 | /** |
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173 | * Looks at the object at the top of the render stack without removing |
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174 | * the {@link IRender} from the stack. |
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175 | * |
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176 | * @return The last (parent) item added to the current render stack. |
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177 | */ |
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178 | IRender renderStackPeek(); |
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179 | ||
180 | /** |
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181 | * Removes the {@link IRender} at the top of the stack, if any. |
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182 | * |
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183 | * @return The removed {@link IRender}, if any. |
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184 | */ |
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185 | IRender renderStackPop(); |
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186 | ||
187 | /** |
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188 | * Pushes the specified render onto the current render stack. |
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189 | * |
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190 | * @param render The {@link IRender} object being pushed. |
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191 | * @return The added {@link IRender}. |
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192 | */ |
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193 | IRender renderStackPush(IRender render); |
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194 | ||
195 | /** |
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196 | * Returns the 1-based position where an object is on this stack. If the object |
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197 | * o occurs as an item in this stack, this method returns the distance from the |
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198 | * top of the stack of the occurrence nearest the top of the stack; the topmost |
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199 | * item on the stack is considered to be at distance 1. The equals method is used |
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200 | * to compare o to the items in this stack. |
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201 | * |
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202 | * @param render The {@link IRender} being searched for. |
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203 | * |
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204 | * @return the 1-based position from the top of the stack where the object is |
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205 | * located; the return value -1 indicates that the object is not on the stack. |
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206 | */ |
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207 | int renderStackSearch(IRender render); |
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208 | ||
209 | /** |
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210 | * Creates a traversable iterator for moving through the stack. |
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211 | * |
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212 | * @return An iterator over the current stack. |
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213 | */ |
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214 | Iterator renderStackIterator(); |
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215 | ||
216 | /** |
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217 | * Removes a previously stored attribute, if one with the given name exists. |
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218 | * |
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219 | * @param name The key name of the attribute to remove. |
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220 | */ |
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221 | ||
222 | void removeAttribute(String name); |
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223 | ||
224 | /** |
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225 | * Renders the given page. Applications should always use this method to render the page, rather |
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226 | * than directly invoking {@link IPage#render(IMarkupWriter, IRequestCycle)}since the request |
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227 | * cycle must perform some setup before rendering. |
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228 | * |
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229 | * @param builder Renders the currently active page using the specified builder. |
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230 | */ |
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231 | ||
232 | void renderPage(ResponseBuilder builder); |
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233 | ||
234 | /** |
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235 | * Allows a temporary object to be stored in the request cycle, which allows otherwise unrelated |
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236 | * objects to communicate. This is similar to <code>HttpServletRequest.setAttribute()</code>, |
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237 | * except that values can be changed and removed as well. |
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238 | * <p> |
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239 | * This is used by components to locate each other. A component, such as |
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240 | * {@link org.apache.tapestry.html.Body}, will write itself under a well-known name into the |
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241 | * request cycle, and components it wraps can locate it by that name. |
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242 | * <p> |
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243 | * Attributes are cleared at the end of each render or rewind phase. |
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244 | * |
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245 | * @param name Key name of the attribute to store. |
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246 | * @param value Value of the attribute. |
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247 | */ |
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248 | ||
249 | void setAttribute(String name, Object value); |
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250 | ||
251 | /** |
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252 | * Invoked just before rendering the response page to get all |
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253 | * {@link org.apache.tapestry.engine.IPageRecorder page recorders}touched in this request cycle |
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254 | * to commit their changes (save them to persistant storage). |
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255 | * |
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256 | * @see org.apache.tapestry.engine.IPageRecorder#commit() |
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257 | */ |
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258 | ||
259 | void commitPageChanges(); |
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260 | ||
261 | /** |
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262 | * Returns the service which initiated this request cycle. |
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263 | * |
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264 | * @return The service associated with current request. |
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265 | * @since 1.0.1 |
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266 | */ |
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267 | ||
268 | IEngineService getService(); |
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269 | ||
270 | /** |
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271 | * Used by {@link IForm forms}to perform a <em>partial</em> rewind so as to respond to the |
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272 | * form submission (using the direct service). |
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273 | * |
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274 | * @param form The form to rewind. |
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275 | * |
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276 | * @since 1.0.2 |
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277 | */ |
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278 | ||
279 | void rewindForm(IForm form); |
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280 | ||
281 | /** |
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282 | * Sets client side form focus off globally for all forms in this request cycle. |
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283 | */ |
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284 | void disableFocus(); |
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285 | ||
286 | /** |
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287 | * Check for global focus being disabled. |
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288 | * @return True if focus is disabled, false otherwise. |
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289 | */ |
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290 | boolean isFocusDisabled(); |
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291 | ||
292 | /** |
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293 | * Invoked by a {@link IEngineService service} to store an array of application-specific |
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294 | * parameters. These can later be retrieved (typically, by an application-specific listener |
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295 | * method) by invoking {@link #getListenerParameters()}. |
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296 | * |
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297 | * @param parameters The parameters to set which will be available as method parameters |
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298 | * to any listeners invoked in this request. |
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299 | * @see org.apache.tapestry.engine.DirectService |
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300 | * @since 4.0 |
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301 | */ |
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302 | void setListenerParameters(Object[] parameters); |
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303 | ||
304 | /** |
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305 | * Returns parameters previously stored by {@link #setListenerParameters(Object[])}. |
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306 | * |
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307 | * @return The current set of bound listener parameters for the current service. |
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308 | * @since 4.0 |
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309 | */ |
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310 | ||
311 | Object[] getListenerParameters(); |
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312 | ||
313 | /** |
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314 | * A convienience for invoking {@link #activate(IPage)}. Invokes {@link #getPage(String)}to |
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315 | * get an instance of the named page. |
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316 | * |
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317 | * @param name The name of the page to activate. |
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318 | * @since 3.0 |
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319 | */ |
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320 | ||
321 | void activate(String name); |
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322 | ||
323 | /** |
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324 | * Sets the active page for the request. The active page is the page which will ultimately |
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325 | * render the response. The activate page is typically set by the {@link IEngineService service}. |
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326 | * Frequently, the active page is changed (from a listener method) to choose an alternate page |
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327 | * to render the response). |
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328 | * <p> |
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329 | * {@link IPage#validate(IRequestCycle)}is invoked on the page to be activated. |
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330 | * {@link PageRedirectException}is caught and the page specified in the exception will be the |
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331 | * active page instead (that is, a page may "pass the baton" to another page using the |
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332 | * exception). The new page is also validated. This continues until a page does not throw |
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333 | * {@link PageRedirectException}. |
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334 | * <p> |
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335 | * Validation loops can occur, where page A redirects to page B and then page B redirects back |
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336 | * to page A (possibly with intermediate steps). This is detected and results in an |
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337 | * {@link ApplicationRuntimeException}. |
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338 | * |
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339 | * @param page The page to activate. |
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340 | * |
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341 | * @since 3.0 |
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342 | */ |
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343 | void activate(IPage page); |
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344 | ||
345 | /** |
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346 | * Returns a query parameter value, or null if not provided in the request. If multiple values |
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347 | * are provided, returns the first value. |
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348 | * |
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349 | * @param name The name of the request parameter to retrieve. |
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350 | * @return The value matching the specified parameter name, or null if none found. |
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351 | * @since 4.0 |
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352 | */ |
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353 | String getParameter(String name); |
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354 | ||
355 | /** |
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356 | * Returns all query parameter values for the given name. Returns null if no values were |
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357 | * provided. |
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358 | * |
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359 | * @param name The name of the parameters to retrieve. |
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360 | * @return The matching multi value array for the specified name, or null if none found. |
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361 | * @since 4.0 |
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362 | */ |
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363 | String[] getParameters(String name); |
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364 | ||
365 | /** |
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366 | * Converts a partial URL into an absolute URL. Prefixes the provided URL with servlet context |
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367 | * path (if any), then expands it to a full URL by prepending with the scheme, server and port |
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368 | * (determined from the current {@link org.apache.tapestry.web.WebRequest request}. |
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369 | * |
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370 | * @param partialURL The url to modify into an absolute url. |
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371 | * @return The converted absolute url representation of the specified partialURL. |
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372 | * @since 4.0 |
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373 | */ |
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374 | ||
375 | String getAbsoluteURL(String partialURL); |
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376 | ||
377 | /** |
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378 | * Forgets any stored changes to the specified page. If the page has already been loaded (and |
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379 | * rolled back) then the loaded page instance is not affected; if the page is only loaded |
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380 | * subsequently, the page instance will not see any persisted property changes. |
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381 | * |
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382 | * @param name The name of the page instance to throw all persistent properties away for. |
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383 | * @since 4.0 |
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384 | */ |
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385 | ||
386 | void forgetPage(String name); |
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387 | ||
388 | /** |
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389 | * Returns the central {@link org.apache.tapestry.services.Infrastructure} object used to |
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390 | * manage the processing of the request. |
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391 | * |
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392 | * @return The {@link Infrastructure} object associated with this request. |
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393 | * @since 4.0 |
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394 | */ |
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395 | ||
396 | Infrastructure getInfrastructure(); |
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397 | ||
398 | /** |
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399 | * Returns the provided string, possibly modified (with an appended suffix) to make it unique. |
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400 | * |
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401 | * @param baseId |
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402 | * the base id from which to generate the unique string. |
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403 | * @return baseId, or baseId with a suffix appended (if the method has been previously invoked |
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404 | * with the same baseId). |
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405 | */ |
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406 | ||
407 | String getUniqueId(String baseId); |
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408 | ||
409 | /** |
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410 | * Returns what <i>will</i> be the next unique id generated based on the given input, but doesn't |
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411 | * store the result. |
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412 | * |
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413 | * @param baseId |
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414 | * the base id from which to generate the unique string. |
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415 | * @return baseId, or baseId with a suffix appended (if the method has been previously invoked |
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416 | * with the same baseId). |
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417 | */ |
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418 | ||
419 | String peekUniqueId(String baseId); |
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420 | ||
421 | /** |
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422 | * Sends a redirect to the client web browser. This is currently a convinience for constructing |
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423 | * and throwing a {@link RedirectException}, but may change in a later release. |
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424 | * |
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425 | * @param URL The url to send a client redirect for. |
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426 | * @since 4.0 |
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427 | * @throws RedirectException |
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428 | */ |
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429 | ||
430 | void sendRedirect(String URL); |
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431 | } |