package com.yc.model;

/**

 * 班级

 * @author Administrator

 *

 */

public class ClassModel {

    private String classCode;

    private String className;

    public String getClassCode() {

        return classCode;

    }

    public void setClassCode(String classCode) {

        this.classCode = classCode;

    }

    public String getClassName() {

        return className;

    }

    public void setClassName(String className) {

        this.className = className;

    }

}

package com.yc.model;

import java.util.Date;

/**

 * 学生表

 * @author WUYF

 *

 */

public class StudentModel {

    private String classCode;

    private String stuCode;

    private String stuName;

    private Integer stuAge;

    private Date stuBirthday = new Date();

    public String getClassCode() {

        return classCode;

    }

    public void setClassCode(String classCode) {

        this.classCode = classCode;

    }

    public String getStuCode() {

        return stuCode;

    }

    public void setStuCode(String stuCode) {

        this.stuCode = stuCode;

    }

    public String getStuName() {

        return stuName;

    }

    public void setStuName(String stuName) {

        this.stuName = stuName;

    }

    public Integer getStuAge() {

        return stuAge;

    }

    public void setStuAge(Integer stuAge) {

        this.stuAge = stuAge;

    }

    public Date getStuBirthday() {

        return stuBirthday;

    }

    public void setStuBirthday(Date stuBirthday) {

        this.stuBirthday = stuBirthday;

    }

}

package com.yc.model;

import java.util.Set;

/**

 * 班级信息

 * @author Administrator

 *

 */

public class ClassInfo {

    private ClassModel classModel;

    private Set<StudentModel> studentModelList;

    public ClassModel getClassModel() {

        return classModel;

    }

    public void setClassModel(ClassModel classModel) {

        this.classModel = classModel;

    }

    public Set<StudentModel> getStudentModelList() {

        return studentModelList;

    }

    public void setStudentModelList(Set<StudentModel> studentModelList) {

        this.studentModelList = studentModelList;

    }

}

package com.yc.test;

import java.io.IOException;

import java.text.SimpleDateFormat;

import java.util.Date;

import java.util.ArrayList;

import java.util.HashSet;

import java.util.List;

import java.util.Set;

import javax.naming.InitialContext;

import com.fasterxml.jackson.core.JsonEncoding;

import com.fasterxml.jackson.core.JsonGenerator;

import com.fasterxml.jackson.core.JsonProcessingException;

import com.fasterxml.jackson.core.type.TypeReference;

import com.fasterxml.jackson.databind.ObjectMapper;

import com.yc.model.ClassInfo;

import com.yc.model.ClassModel;

import com.yc.model.StudentModel;

@SuppressWarnings("unused")

public class jacksonTest {

    /**

     * @param args

     */

    public static void main(String[] args) {

        // TODO Auto-generated method stub

        init();

        doTest();

        testJsonGenerate();

    }

    /******************** 变量定义   ************************/

    private static ObjectMapper jsonMapper = new ObjectMapper();

    private static ClassInfo classInfo = new ClassInfo();

    private static JsonGenerator jsonGenerator = null;

    /******************** 初始化 **************************/

    private static void init()

    {

        classInfo.setStudentModelList(new HashSet<StudentModel>());

        // 班级数据初骀化

        ClassModel classModel = new ClassModel();

        classModel.setClassCode("001");

        classModel.setClassName("计0312班");

        classInfo.setClassModel(classModel);

        // 学生数据初始化

        for(Integer i= 1; i<5;i++)

        {

            StudentModel studentModel = new StudentModel();

            studentModel.setClassCode(classModel.getClassCode());

            studentModel.setStuCode("00" + i.toString());

            studentModel.setStuName("学生_" + studentModel.getStuCode());

            studentModel.setStuAge(18 + i);

            classInfo.getStudentModelList().add(studentModel);

        }

        System.out.println(classInfo);

    }

    /******************** 测试主体 **************************/

    private static void testJsonGenerate()

    {

        try {

            jsonGenerator = jsonMapper.getFactory().createGenerator(System.out,JsonEncoding.UTF8);

            jsonGenerator.writeObject(classInfo);

            jsonGenerator.flush();

            jsonGenerator.close();

        } catch (IOException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

    /**

     * @throws IOException

     *

     */

    private static void doTest()

    {

        try {

            SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");

            jsonMapper.setDateFormat(dateFormat);

            ClassInfo classInfoTmp = new ClassInfo();

            String classInfoJsonString = jsonMapper.writeValueAsString(classInfo);

            System.out.println("classInfoJsonString:");

            System.out.println(classInfoJsonString);

            classInfoTmp = jsonMapper.readValue(classInfoJsonString, ClassInfo.class);

            String classInfoJsonTmpString = jsonMapper.writeValueAsString(classInfoTmp);

            System.out.println("classInfoJsonTmpString:");

            System.out.println(classInfoJsonTmpString);

        } catch (JsonProcessingException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        } catch (IOException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

}

使用Jackson时转换JSON时，日期格式设置

近日，使用Jackson转化JSON对象的时候，显示的时候，日期始终显示不正确，输出的日期是一串数字代表的时间戳，不符合要求，所以想到Jackson应当有方法设置输出的日期格式。后来一查果然有两种方式来实现：

1.普通的方式：

默认是转成timestamps形式的，通过下面方式可以取消timestamps。

objectMapper.configure(SerializationConfig.Feature.WRITE_DATES_AS_TIMESTAMPS, false);

 这样将使时间生成使用所谓的use a [ISO-8601 ]-compliant notation, 输出类似如下格式的时间: "1970-01-01T00:00:00.000+0000".

当然也可以自定义输出格式：

objectMapper.getSerializationConfig().setDateFormat(myDateFormat);

myDateFormat对象为java.text.DateFormat，具体使用清查java API

2.annotaion的注释方式：

先定义自己需要的格式，例如：

import java.io.IOException;

import java.text.SimpleDateFormat;

import java.util.Date;

import org.codehaus.jackson.JsonGenerator;

import org.codehaus.jackson.JsonProcessingException;

import org.codehaus.jackson.map.JsonSerializer;

import org.codehaus.jackson.map.SerializerProvider;

/**

 *  java日期对象经过Jackson库转换成JSON日期格式化自定义类

 * @author godfox

 * @date 2010-5-3

 */

public class CustomDateSerializer extends JsonSerializer<Date> {

        @Override

        public void serialize(Date value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {

                SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");

                String formattedDate = formatter.format(value);

                jgen.writeString(formattedDate);

        }

}

 然后在你的POJO上找到日期的get方法

 @JsonSerialize(using = CustomDateSerializer.class)

        public Date getCreateAt() {

                return createAt;

        }

            ObjectMapper jsonMapper = new ObjectMapper();

            rtnResult = jsonMapper.writeValueAsString(invoiceDtos);

            List<InvoiceDetail> deJson = (List<InvoiceDetail>)jsonMapper.readValue(rtnResult, new TypeReference<List<InvoiceDetail>>() {});