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  • 暑期项目经验(六)--struts+json

                  struts+json

    tips:注意 struts.xml配置,  json-default  及引入 struts2-json-plugin-2.1.8.1.jar 包

    1、json基础知识

     JSON(JavaScript Object Notation)是一种轻量级的数据格式,采用完全独立于语言的文本格式,是理想的数据交换格式。同时,JSON是Javascript原生格式,这意 味着在javascript中处理JSON数据不需要任何特殊的API或工具包,而且效率非常高。

         JSON的结构如下:

    • “名称/值”对的集合(A collection of name/value pairs)。不同的语言中,它被理解为对象(object),纪录(record),结构(struct),字典(dictionary),哈希表(hash table),有键列表(keyed list),或者关联数组 (associative array)。
    • 值的有序列表(An ordered list of values)。在大部分语言中,它被理解为数组(array)

          一个标准的json格式:

    {"name":"jifeng","company":"taobao"}

    2.json的解析

    json的解析方法共有两种:1. eval() ; 2.JSON.parse() ; 3.evalJSON()。具体使用方法如下:

    var jsonstr = '{"name":"jifeng","company":"taobao"}';
    //eval function
    var evalJson = eval('(' + jsonstr + ')');
    // JSON.parse function
    var JSONParseJson = JSON.parse(jsonstr);
    
    //这个引入property.js
    var obj = jsonstr.evalJSON();

    3.struts2的json响应的param类型   param name=" XX "

    root:只包含xx对象excludeProperties  :除了xx之外的集合includeProperties : 包含xx的集合
    wrapPrefix :json结果开头添加xx(比如<paramname="wrapPrefix">[</param>)
    wrapSuffix :同上,只不过是结尾
    ignoreHierarchy :转化时是否忽略继承关系true/false
    enumAsBean : 是否将枚举当做一个bean处理
    enableGZIP :是否支持gzip压缩输出
    noCache :是否缓存
    excludeNullProperties : 是否转化输出 null值
    statusCode :设置响应代号比如 304
    callbackParameter : JSONP跨域访问的回调设置
    contentType : 输出类型

    4.fastjson  实例

    实体类:

    package com.pxj.fastjson.entity;
    
    public class Student {
         private int id;  
            private String name;  
            private int age;  
              
            /** 
             * 默认的构造方法必须不能省,不然不能解析 
             */  
              
            public Student(){  
                  
            }  
            public Student(int id,String name,int age) {  
                this.id = id;  
                this.name = name;  
                this.age = age;  
            }  
          
            public int getId() {  
                return id;  
            }  
          
            public void setId(int id) {  
                this.id = id;  
            }  
          
            public String getName() {  
                return name;  
            }  
          
            public void setName(String name) {  
                this.name = name;  
            }  
          
            public int getAge() {  
                return age;  
            }  
          
            public void setAge(int age) {  
                this.age = age;  
            }  
              
            @Override  
            public String toString() {  
                return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";  
            }  
    }
    package com.pxj.fastjson.entity;
    
    import java.util.List;
    
    public class Teacher {
        private int id;  
        private String name;  
          
        private List<Student> students;  
          
      
        /** 
         * 默认的构造方法必须不能省,不然不能解析 
         */  
        public Teacher() {  
              
        }  
        public Teacher(int id,String name) {  
            this.id = id;  
            this.name = name;  
        }  
          
        public int getId() {  
            return id;  
        }  
        public void setId(int id) {  
            this.id = id;  
        }  
        public String getName() {  
            return name;  
        }  
        public void setName(String name) {  
            this.name = name;  
        }  
      
        public List<Student> getStudents() {  
            return students;  
        }  
        public void setStudents(List<Student> students) {  
            this.students = students;  
        }  
        @Override  
        public String toString() {  
            return "Teacher [id=" + id + ", name=" + name + ", mStudents="  
                    + students + "]";  
        }  
    }

     测试类:

    package com.pxj.fastjson.demo;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import org.junit.Test;
    
    import com.alibaba.fastjson.JSON;
    import com.alibaba.fastjson.TypeReference;
    import com.alibaba.fastjson.serializer.SimplePropertyPreFilter;
    import com.pxj.fastjson.entity.Student;
    import com.pxj.fastjson.entity.Teacher;
    
    public class Demo {
        @Test
        public void test1() {
            Student student = new Student(0, "Aaron", 24);
            System.out.println(JSON.toJSONString(student));
        }
        //{"age":24,"id":0,"name":"Aaron"}
    
        @Test
        public void test2() {
            List<Student> students = new ArrayList<Student>();
            for (int i = 0; i < 5; i++) {
                Student stu = new Student(i, "Student" + i, 18 + i);
                students.add(stu);
            }
            System.out.println(JSON.toJSONString(students));
        }
    
        @Test
        public void test3() {
            List<Teacher> teaList = new ArrayList<Teacher>();
            for (int i = 0; i < 10; i++) {
                Teacher teacher = new Teacher(i, "Teacher " + i);
                List<Student> stus = new ArrayList<Student>();
                for (int j = 0; j < 4; j++) {
                    Student s = new Student(j, "Student" + j, 18 + j);
                    stus.add(s);
                }
                teacher.setStudents(stus);
                teaList.add(teacher);
            }
            String jsonTeach = JSON.toJSONString(teaList);
            System.out.println("fastjson = " + jsonTeach);
        }
    
        // 按照标准的json 格式输出
        @Test
        public void test4() {
            Student student = new Student(0, "Aaron", 24);
            System.out.println(JSON.toJSONString(student, true));
        }
    
        // 实体类中的某个字段或某几个不进行解析呢
        @Test
        public void test5() {
            List<Student> students = new ArrayList<Student>();
            for (int i = 0; i < 5; i++) {
                Student stu = new Student(i, "Student" + i, 18 + i);
                students.add(stu);
            }
            SimplePropertyPreFilter filter = new SimplePropertyPreFilter(Student.class, "id", "age");
            String jsonStu = JSON.toJSONString(students, filter);
            System.out.println(jsonStu);
        }
        //反序列化主要使用的是JSON.parseObject(str,class); 它就能把我们的str 转化为class 类型的对象,当然还有更复杂的对象
        @Test
        public void test6() {
            List<Student> students = new ArrayList<Student>();
            for (int i = 0; i < 5; i++) {
                Student stu = new Student(i, "Student" + i, 18 + i);
                students.add(stu);
            }
            String jsonStu = JSON.toJSONString(students);
            List<Student> stu =JSON.parseObject(jsonStu, new TypeReference<List<Student>>(){});  
            for(int i=0;i<stu.size();i++)   
            {  
                System.out.println(stu.get(i));  
            }  
        }
    }

     5. struts+json实例

    index.jsp

    <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
    <%
    String path = request.getContextPath();
    String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
    %>
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
        <head>
            <base href="<%=basePath%>">
            <title>获取</title>
            <script type="text/javascript" src="js/jquery-1.4.3.js">
    </script>
            <script type="text/javascript">
    function loadInfo() {
        $("#info").load("loadInfo");
    }
    </script>
        </head>
        <body>
            <input type="button" value="获取" id="btnGet" onclick="loadInfo()" />
            <div id="info"></div>
        </body>
    </html>

     comment.java

    package com.pxj.entity;
    
    public class Comment {
        private long id;
        private String nickname;
        private String content;
        public long getId() {
            return id;
        }
        public void setId(long id) {
            this.id = id;
        }
        public String getNickname() {
            return nickname;
        }
        public void setNickname(String nickname) {
            this.nickname = nickname;
        }
        public String getContent() {
            return content;
        }
        public void setContent(String content) {
            this.content = content;
        }   
    }

     InfoAction.java

    package com.pxj.action;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import org.apache.struts2.json.annotations.JSON;
    
    import com.pxj.entity.Comment;
    
    public class InfoAction {
        private static final long serialVersionUID = 1359090410097337654L;
    
        private List<Comment> comments = new ArrayList<Comment>();
        //没getter and setter方法的属性不会被串行化到JSON
        @SuppressWarnings("unused")
        private String title;
        //!!!使用transient修饰的属性也会被串行化到JSON
        private transient String content;
    
        public String loadInfo() {
            title="123木头人";
            content="你是木头人,哈哈。";
            loadComments();
            return "success";
        }
    
        /**
         * 加载留言信息
         */
        private void loadComments() {
            Comment com1 = new Comment();
            com1.setContent("很不错嘛");
            com1.setId(1);
            com1.setNickname("纳尼");
            Comment com2 = new Comment();
            com2.setContent("哟西哟西");
            com2.setId(2);
            com2.setNickname("小强");
            comments.add(com1);
            comments.add(com2);
        }
        //为了使content对象不被串行化到JSON,在不能舍弃其getter setter方法的时候,我们可以这样在content的getter方法上面加上注解:@JSON(serialize=false)
        @JSON(serialize=false)
        public List<Comment> getComments() {
            return comments;
        }
    
        public void setComments(List<Comment> comments) {
            this.comments = comments;
        }
    
        public static long getSerialversionuid() {
            return serialVersionUID;
        }
    
        public String getContent() {
            return content;
        }
    
        public void setContent(String content) {
            this.content = content;
        }
    }

     struts.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">
    <struts>
        <package name="default" namespace="/" extends="json-default">
        
            <action name="loadInfo" class="com.pxj.action.InfoAction" method="loadInfo">
                <result name="success" type="json"></result>
            </action>
    </struts>
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  • 原文地址:https://www.cnblogs.com/pxjgood/p/3991412.html
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