xml解析工具包 Xstream的示例代码详解

特点

1. 简化的API; 

2. 无映射文件; 

3. 高性能,低内存占用; 

4. 整洁的XML; 

5. 不需要修改对象，支持内部私有字段；

6. 不需要setter/getter方法,final字段;

7. 提供序列化接口; 

8. 自定义转换类型策略; 

9. 详细的错误诊断; 

Xstream常用注解

@XStreamAlias("message") 别名注解，作用目标：类，字段

@XStreamImplicit 隐式集合  

@XStreamImplicit(itemFieldName="part")  作用目标：集合字段  

@XStreamConverter(SingleValueCalendarConverter.class) 注入转换器，作用目标： 对象  

@XStreamAsAttribute 转换成属性，作用目标：字段  

@XStreamOmitField 忽略字段，作用目标：字段  

示例

1. 解析XML工具类

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.*;

/**
 * 输出xml和解析xml的工具类
 */
public class XmlUtil {
    private static final Logger logger = LoggerFactory.
            getLogger(XmlUtil.class);

    /**
     * java 转换成xml
     * @param obj 对象实例
     * @return String xml字符串
     * @Title: toXml
     * @Description: TODO
     */
    public static String toXml(Object obj) {
        //XStream xstream=new XStream(); //默认使用xpp解析器
        //指定编码解析器
        XStream xstream = new XStream(new DomDriver("utf-8"));
        //启用注解识别
        xstream.processAnnotations(obj.getClass());
        return xstream.toXML(obj);
    }

    /**
     * 将传入xml文本转换成Java对象
     * @param xmlStr
     * @param cls xml对应的class类
     * @return T  xml对应的class类的实例对象
     */
    public static <T> T toBean(String xmlStr, Class<T> cls) {
        XStream xstream = new XStream();
        xstream.processAnnotations(cls);
        T obj = (T) xstream.fromXML(xmlStr);
        return obj;
    }

    /**
     * 写到xml文件中去
     * @param obj      对象
     * @param absPath  绝对路径
     * @param fileName 文件名
     */
    public static boolean toXMLFile(Object obj, String absPath, String fileName) {
        String strXml = toXml(obj);
        String filePath = absPath + fileName;
        File file = new File(filePath);
        if (!file.exists()) {
            try {
                file.createNewFile();
            } catch (IOException e) {
                logger.error("file creation failed, cause is {}", e);
                return false;
            }
        }
        OutputStream ous = null;
        try {
            ous = new FileOutputStream(file);
            ous.write(strXml.getBytes());
            ous.flush();
        } catch (Exception e1) {
            logger.error("file write failed, cause is {}", e1);
            return false;
        } finally {
            if (ous != null)
                try {
                    ous.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
        }
        return true;
    }

    /**
     * 从xml文件读取报文
     * @param absPath  绝对路径
     * @param fileName 文件名
     * @param cls
     */
    public static <T> T toBeanFromFile(String absPath, String fileName, Class<T> cls) throws Exception {
        String filePath = absPath + fileName;
        InputStream ins = null;
        try {
            ins = new FileInputStream(new File(filePath));
        } catch (Exception e) {
            throw new Exception("read {" + filePath + "} file failed！", e);
        }
        XStream xstream = new XStream();
        xstream.processAnnotations(cls);
        T obj = null;
        try {
            obj = (T) xstream.fromXML(ins);
        } catch (Exception e) {
            throw new Exception("parse {" + filePath + "} file failed！", e);
        }
        if (ins != null)
            ins.close();
        return obj;
    }
}

2. 编写Teacher类

import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamAsAttribute;
import com.thoughtworks.xstream.annotations.XStreamImplicit;
import java.util.List;

@XStreamAlias(value = "teacher")
public class Teacher {
    @XStreamAsAttribute
    private String name;
    @XStreamAsAttribute
    private String phone;
    @XStreamAsAttribute
    private int age;
    @XStreamImplicit(itemFieldName = "student")
    private List<Student> students;

    public Teacher() {
    }

    public Teacher(String name, String phone, int age, List<Student> students) {
        this.name = name;
        this.phone = phone;
        this.age = age;
        this.students = students;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public List<Student> getStudents() {
        return students;
    }

    public void setStudents(List<Student> students) {
        this.students = students;
    }
}

3. 编写Student类

import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamAsAttribute;
@XStreamAlias(value = "student")
public class Student {
    @XStreamAsAttribute
    private String name;
    @XStreamAsAttribute
    private int age;
    @XStreamAsAttribute
    private String address;

    public Student() {
    }

    public Student(String name, int age, String address) {
        this.name = name;
        this.age = age;
        this.address = address;
    }

    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;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

4. Test测试类

import java.util.ArrayList;
import java.util.List;

public class Test {
    public static void main(String[] args) {
        Student student1 = new Student("Aaron", 24, "广州");
        Student student2 = new Student("Abel", 23, "北京");
        List<Student> students = new ArrayList<>();
        students.add(student1);
        students.add(student2);
        Teacher teacher = new Teacher("Dave", "020-123456", 46, students);
        String xml = XmlUtil.toXml(teacher);
        System.out.println(xml);
    }
}

5. 运行结果

<teacher name="Dave" phone="020-123456" age="46">
  <student name="Aaron" age="24" address="广州"/>
  <student name="Abel" age="23" address="北京"/>
</teacher>

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