微信小程序实战,与后台交互

index.wxml

<view class="container">
  <text>{{txt}}</text>
  <input name="name" type="text" id='text' bindchange="xyz"/>
  <button id="btn" bindtap="abc" >提交</button>
</view>

index.js

//index.js
//获取应用实例
const app = getApp()
Page({
  data: {
    motto: 'Hello World',
    userInfo: {},
    hasUserInfo: false,
    canIUse: wx.canIUse('button.open-type.getUserInfo'),
    txt:"",
  },
  //事件处理函数
  bindViewTap: function() {
    wx.navigateTo({
      url: '../logs/logs'
    })
  },

  abc:function(e){//该函数用于和后台交互
   // var v = e
    var v = this.txt;
    var self=this;            //关键代码,这要操作程序无法运行
    wx.request({
      url: 'https://域名/jous/hello.do', //仅为示例，并非真实的接口地址
      data: {
        name:v,
      },
      header: {
        'content-type': 'application/json' // 默认值
      },
      success(res) {
        //console.log(res.data)
        this.txt=res.data//把交互的参数值赋值给全局变量
        console.log("aaa" + this.txt)//控制台输出变量

        self.setData({//动态设置显示的值
          txt: this.txt
        })
      }
    })
  },

  xyz: function (e) {//从输入框获取数据
    var v = e.detail.value
    this.txt=v;//将获取到的值赋值给中间变量
  },

})

JAVA代码

	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String name = request.getParameter("name");
		String msg  = "Hello"+name;
		JsonUtil.printJson(response,msg);
	}

JAVA 转Json代码

	public static void printJson(HttpServletResponse response, Object obj) throws IOException {
		// 返回数据，返回数据类型是json
		response.setContentType("application/json");
		// 返回数据编码UTF-8
		response.setCharacterEncoding("UTF-8");
		// 返回数据，通过gson将数据返回给Ajax 通过gson工具提高工作效率
		response.getWriter().write(new Gson().toJson(obj));
	}