Ext结合DWR的关键代码（运行成功的DWRProxy）

关键代码如下：

Store为：

1. var ds = new Ext.data.Store({
3.     proxy: new Ext.data.DWRProxy({
4.         callback: Folder.getMessageList,
5.          params: {
6.              start: '0',
7.              limit: PAGE_SIZE
8.          }
9.      }),
10.     
11.     //    proxy: new Ext.data.MemoryProxy(messageList),
12.     
13.     reader: new Ext.data.ObjectReader({
14.         root: 'messages',
15.         totalProperty: 'total'//用来让Ext的PagingToolbar组件分析总页数
16.     }, [{
17.         name: 'messageId'
18.     }, {
19.         name: 'from'
20.     }, {
21.         name: 'subject'
22.     }, {
23.         name: 'sendTime'
24.     }, {
25.         name: 'contentText'
26.     }])
28. });
30. //在进行DWR请求之前，默认在请求参数中添加当前文件夹ID。这样DWR请求中包括的请求参数为:folderId，start，limit
31. ds.on('beforeload', function(){
32.     Ext.apply(this.baseParams, {
33.         folderId: currentFolderId
34.     });
35. });
37. ds.load({
38.         params: {
39.             start: currentStart,
40.             limit: currentLimit
41.         }
42.     });//指定起始位置以及个数

自定义的DWRProxy和ObjectReader：

1. Ext.data.DWRProxy = function(config){
2.       Ext.data.DWRProxy.superclass.constructor.call(this);
3.       Ext.apply(this, config ||
4.       {});
5.   };
6.   
7.   7Ext.extend(Ext.data.DWRProxy, Ext.data.DataProxy, {
8.       //DWR请求
9.       load: function(params, reader, callback, scope, arg){
10.          currentStart = params.start;//保存当前页记录起始位置
11.          currentLimit = params.limit;//保存当前页记录的个数
12.          document.dwr = {
13.              params: params,
14.              reader: reader,
15.              callback: callback,
16.              scope: scope,
17.              arg: arg
18.          };
19.          //处理请求参数，将各个请求参数转换到Array中
20.          var callParams = new Array();
21.          callParams.push(params.folderId);//当前文件夹ID
22.          callParams.push(params.start);//请求的起始位置
23.          callParams.push(params.limit);//请求的个数
24.          if (this.params !== undefined && this.params !== null) {
25.              this.callback.call(this, callParams, this.loadResponse);//DWR请求
26.          }
27.          else {
28.              this.callback.call(this, this.loadResponse);
29.          }
30.      },
31.      //处理DWR返回
32.      loadResponse: function(response){
33.          var dwr = document.dwr;
34.          try {
35.              //IE throws an exception 'Error: TypeError, Object does not support this operation'   
36.              //so use trycatch to suppress this exception   
37.              delete document.dwr;//ie不支持delete
38.          } 
39.          catch (e) {
40.          }
41.          var result;
42.          try {
43.              result = dwr.reader.read(response);//读取请求返回的json
44.          } 
45.          catch (e) {
46.              //this.fireEvent("loadexception",this,dwr,response,e);   
47.              dwr.callback.call(dwr.scope, null, dwr.arg, false);
48.              return;
49.          }
50.         dwr.callback.call(dwr.scope, result, dwr.arg, true);
51.      },
52.      failure: function(errorString, exception){
53.          console.log("DWR " + exception);
54.     },
55.      update: function(params, records){
56.      }
57.  });
59.  //自定义一个用于处理返回消息列表的Reader
60.  Ext.data.ObjectReader = function(meta, recordType){
61.      Ext.data.ObjectReader.superclass.constructor.call(this, meta, recordType);
62.  };
64.  Ext.extend(Ext.data.ObjectReader, Ext.data.DataReader, {
65.      //处理DWR返回
66.      read: function(response){
67.          var responseDecode = Ext.util.JSON.decode(response);//注意，由java的json-lib生成的json串需要解码一下
68.          var data = responseDecode.messages;
69.          var sid = this.meta ? this.meta.id : null;
70.          var recordType = this.recordType, fields = recordType.prototype.fields;
71.         var records = [];
72.          var root = data;
73.         for (var i = 0; i < root.length; i++) {
74.              var obj = root[i];
75.              var values = {};
76.              var id = obj[sid];
77.              for (var j = 0, jlen = fields.length; j < jlen; j++) {
78.                  var f = fields.items[j];
79.                  var k = (f.mapping !== undefined && f.mapping !== null) ? f.mapping : f.name;
80.                  var v = null;
81.                 var idx = k.indexOf(".");
82.                  if (idx == -1) {
83.                      v = obj[k] !== undefined ? obj[k] : f.defaultValue;
84.                  }
85.                  else {
86.                      var k1 = k.substr(0, idx);
87.                      var k2 = k.substr(idx + 1);
88.                      if (obj[k1] == undefined) {
89.                          v = f.defaultValue;
90.                      }
91.                      else {
92.                          var obj2 = obj[k1];
93.                          v = obj2[k2] !== undefined ? obj2[k2] : f.defaultValue;
94.                     }
95.                  }
96.                  v = f.convert(v);
97.                  values[f.name] = v;
98.              }
99.              var record = new recordType(values, id);
100.             records[records.length] = record;
101.         }
102.         return {
103.             records: records,//返回的消息列表记录
104.             totalRecords: responseDecode.total//总个数
105.         };
106.     }
107. });