关于ajax请求，返回json数据格式

使用servlet测试

后台数据为：返回类型没有设置（方式一）

 String str = "["+
             "{ id:1, pId:0, name:\"可折腾的父节点 1\", t:\"我很普通，随便 展开/折叠 我吧\", open:false},"+
             "{ id:11, pId:1, name:\"叶子节点 - 1\", t:\"我老爸很普通，随便折腾他吧\"},"+
             "{ id:12, pId:1, name:\"可折腾的父节点 2\", t:\"我和我老爸都很普通，随便折腾我和他吧\", open: false},"+
             "{ id:121, pId:12, name:\"父节点 - 121\", t:\"我老爸很普通，随便折腾他吧\", open:true},"+
             "{ id:1211, pId:121, name:\"父节点 - 1211\", t:\"我老爸很普通，随便折腾他吧\", open:false},"+
             "{ id:1212, pId:1211, name:\"叶子节点 - 1212\", t:\"我老爸很普通，随便折腾他吧\"},"+
             "{ id:1213, pId:121, name:\"父节点 - 1213\", t:\"我老爸很普通，随便折腾他吧\", open:false},"+
             "{ id:1214, pId:1213, name:\"叶子节点 - 1214\", t:\"我老爸很普通，随便折腾他吧\"},"+
             "{ id:123, pId:12, name:\"叶子节点 - 23\", t:\"我老爸很普通，随便折腾他吧\"},"+
             "{ id:13, pId:1, name:\"叶子节点 - 3\", t:\"我老爸很普通，随便折腾他吧\"},"+
             "{ id:2, pId:1, name:\"无法折叠的父节点\", t:\"休想让我折叠起来...除非你用 expandAll 方法\", open:false, collapse:false},"+
             "{ id:21, pId:2, name:\"叶子节点2 - 1\", t:\"哈哈哈，我老爸NB吧，不能折叠吧？\"},"+
             "{ id:22, pId:21, name:\"叶子节点2 - 2\", t:\"哈哈哈，我老爸NB吧，不能折叠吧？\"},"+
             "{ id:23, pId:21, name:\"叶子节点2 - 3\", t:\"哈哈哈，我老爸NB吧，不能折叠吧？\"},"+
             "{ id:3, pId:2, name:\"无法展开的父节点\", t:\"就凭你也想展开我？难呀...嘿嘿, 除非你用 expandAll 方法\", open:false, expand:true},"+
             "{ id:31, pId:3, name:\"叶子节点3 - 1\", t:\"居然让你看到了...莫非你用了全部节点展开？\"},"+
             "{ id:32, pId:31, name:\"叶子节点3 - 2\", t:\"居然让你看到了...莫非你用了全部节点展开？\"},"+
             "{ id:33, pId:31, name:\"叶子节点3 - 3\", t:\"居然让你看到了...莫非你用了全部节点展开？\"},"+
             "{ id:4, pId:3, name:\"空空的父节点 1\", t:\"一无所有...除了我自己\", isParent:true, open:false}"+
         "]";

前端使用$.post接收，没有问题，能够加载出树结构

 $.POST('/TestServlet',{},function(data){
             var nodes = eval("("+data+")");
             $.fn.zTree.init($("#tree"), setting, nodes);
         });

使用ajax接收，配置呢type为json，会提示加载失败

 $.ajax({
             type: "POST",
             url: '/TestServlet',
             timeout: 1000,
             data: {
                 key1: "value1",
                 key2: "value2"
             },
             async: true,
             dataType: "json",
             error: function(){
                 alert("请求失败！");
             },
             success: function(data){
                 treeObj = $.fn.zTree.init($("#tree"), setting, data);
             }
         }); 

见后端的字符串修改：键上加了引号（方式二）

         String str = "["+
             "{ \"id\":1, \"pId\":0, \"name\":\"可折腾的父节点 1\", \"t\":\"我很普通，随便 展开/折叠 我吧\", \"open\":true},"+
             "{ \"id\":11, \"pId\":1, \"name\":\"叶子节点 - 1\", \"t\":\"我老爸很普通，随便折腾他吧\"},"+
             "{ \"id\":12, \"pId\":1, \"name\":\"可折腾的父节点 2\", \"t\":\"我和我老爸都很普通，随便折腾我和他吧\", \"open\": false},"+
             "{ \"id\":121, \"pId\":12, \"name\":\"父节点 - 121\", \"t\":\"我老爸很普通，随便折腾他吧\", \"open\":true},"+
             "{ \"id\":1211, \"pId\":121, \"name\":\"父节点 - 1211\", \"t\":\"我老爸很普通，随便折腾他吧\", \"open\":false},"+
             "{ \"id\":1212, \"pId\":1211, \"name\":\"叶子节点 - 1212\", \"t\":\"我老爸很普通，随便折腾他吧\"},"+
             "{ \"id\":1213, \"pId\":121, \"name\":\"父节点 - 1213\", \"t\":\"我老爸很普通，随便折腾他吧\", \"open\":false},"+
             "{ \"id\":1214, \"pId\":1213, \"name\":\"叶子节点 - 1214\", \"t\":\"我老爸很普通，随便折腾他吧\"},"+
             "{ \"id\":123, \"pId\":12, \"name\":\"叶子节点 - 23\", \"t\":\"我老爸很普通，随便折腾他吧\"},"+
             "{ \"id\":13, \"pId\":1, \"name\":\"叶子节点 - 3\", \"t\":\"我老爸很普通，随便折腾他吧\"},"+
             "{ \"id\":2, \"pId\":1, \"name\":\"无法折叠的父节点\", \"t\":\"休想让我折叠起来...除非你用 openAll 方法\", \"open\":false, \"collapse\":false},"+
             "{ \"id\":21, \"pId\":2, \"name\":\"叶子节点2 - 1\", \"t\":\"哈哈哈，我老爸NB吧，不能折叠吧？\"},"+
             "{ \"id\":22, \"pId\":21, \"name\":\"叶子节点2 - 2\", \"t\":\"哈哈哈，我老爸NB吧，不能折叠吧？\"},"+
             "{ \"id\":23, \"pId\":21, \"name\":\"叶子节点2 - 3\", \"t\":\"哈哈哈，我老爸NB吧，不能折叠吧？\"},"+
             "{ \"id\":3, \"pId\":2, \"name\":\"无法展开的父节点\", \"t\":\"就凭你也想展开我？难呀...嘿嘿, 除非你用 openAll 方法\", \"open\":false, \"expand\":true},"+
             "{ \"id\":31, \"pId\":3, \"name\":\"叶子节点3 - 1\", \"t\":\"居然让你看到了...莫非你用了全部节点展开？\"},"+
             "{ \"id\":32, \"pId\":31, \"name\":\"叶子节点3 - 2\", \"t\":\"居然让你看到了...莫非你用了全部节点展开？\"},"+
             "{ \"id\":33, \"pId\":31, \"name\":\"叶子节点3 - 3\", \"t\":\"居然让你看到了...莫非你用了全部节点展开？\"},"+
             "{ \"id\":4, \"pId\":3, \"name\":\"空空的父节点 1\", \"t\":\"一无所有...除了我自己\", \"isParent\":true, \"open\":false}"+
         "]";

且设置返回值类型：

response.setContentType("application/json; charset=utf-8");

就可以使用ajax设置type为json接收数据。

注意：后台设置json格式返回时，键上要加引号。如果键上没加引号，但是又设置呢返回值为json，通过浏览器，可以正常加载出数据，但是在使用ajax请求时，会失败。