【webservice】servlet生成json格式数据小结         返回主页

最近在思考后台service生成json格式数组的实现方式，今天复习servlet看到response对象突然想到可以使用它进行数据的输出，因为即便是json也只是一种数据的表现形式，response本身并不关心其具体实现方式，因此只要生成该格式并由其输出就可以用其他方式包括不限于android客户端进行解析。

代码及分析（本项目使用org.json进行json数据的组装和输出，使用MySQL作为数据持久层）

代码结构图

conn.java连接数据库方法

package JsonFromDB;

import java.sql.Connection;
import java.sql.DriverManager;

    public class conn {
    public Connection getCon() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost/test?useUnicode=true&characterEncoding=utf-8";
            String user = "snowalker";
            String password = "admin";
            Connection conn = DriverManager.getConnection(url, user, password);
            System.out.println("connnection success");
            System.out.println(conn.getMetaData().getURL());

            return conn;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}

student.java,学生POJO类，定义一些学生属性

package JsonFromDB;

public class student {
    //姓名
    private String name;
    //年龄
    private int age;
    //学校
    private String schoolName;
    //专业
    private String major;
    public String getName() {
        return name;
    }
    public String setName(String name) {
        return this.name = name;
    }
    public int getAge() {
        return age;
    }
    public int setAge(int age) {
        return this.age = age;
    }
    public String getSchoolName() {
        return schoolName;
    }
    public String setSchoolName(String schoolName) {
        return this.schoolName = schoolName;
    }
    public String getMajor() {
        return major;
    }
    public String setMajor(String major) {
        return this.major = major;
    }
}

类JsonEncodeDemo.java是一个servlet，继承了HttpServlet，作为对外数据呈现接口和json数据组装容器

package JsonFromDB;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.json.JSONException;
import org.json.JSONObject;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;
import formVerify.conn;

@WebServlet("/JsonEncodeDemo")
public class JsonEncodeDemo extends HttpServlet {
private static final long serialVersionUID = 1L;

public JsonEncodeDemo() {
    super();
}

protected void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    this.doPost(request, response);
}

protected void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    request.setCharacterEncoding("UTF-8");
    // 设置响应的文本类型为HTML，字符编码为UTF-8
    response.setContentType("text/html;charset=UTF-8");
    response.setCharacterEncoding("UTF-8");

    PrintWriter out = response.getWriter();     
    //连接数据库
    java.sql.ResultSet rs = null;
    Connection connection = (Connection) new conn().getCon();

    System.out.print("数据库连接成功");

    Statement statement;
    //获取数据库中数据到对应字段
    student student = new student();
    String name = null;
    int age = 0;
    String schoolName = null;
    String major = null;
    try {
        statement = (Statement) connection.createStatement();
        rs = statement.executeQuery("select * from student where name = 'snowalker'");
        while (rs.next()) {
            System.out.println();
            name = student.setName(rs.getString("name"));
            age = student.setAge(rs.getInt("age"));
            schoolName = student.setSchoolName(rs.getString("schoolName"));
            major = student.setMajor(rs.getString("major"));
        }


    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    //组装json数据
    JSONObject student1 = new JSONObject();

    try {
        student1.put("name", name);
        student1.put("age", age);
        student1.put("schoolName", schoolName);
        student1.put("major", major);
    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    out.print(student1);
}

}

数据库中数据

发布并运行该web应用，访问http://localhost:8080/HelloServlet/JsonEncodeDemo看到如下结果，表明该json数据发布成功

接下来就可以使用客户端对其进行解析

小结：

当前主流的webservice架构还是SOAP和RESTful。本文介绍的方式属于非主流的方式，不过对于小规模的应用来说这样的方式也是可以接受的。

今后的文章中将陆续介绍其他的实现方式。GN。

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