利用Digester实现xml和bean之间的转换（二）

Digester框架属于Jakarta Commons，它以规则和模式为基础处理XML文档。与SAX和DOM之类的标准API相比，Digester不涉及太多的细节问题，非常适合于对XML文档进行简单的处理。
比如要解析如下的xml文件

<persons>  
    <person name="tom">
        <age>4</age>  
        <address>  
            <street>no1street</street>  
            <belongarea>us</belongarea>  
        </address>  
        <creditcard>  
            <limit code="123" pwd="abc">1000</limit>  
            <bank>ICBC</bank>  
        </creditcard>  
        <creditcard>  
            <limit code="321" pwd="cba">2000</limit>  
            <bank>CBC</bank>  
        </creditcard>  
    </person>  
    <person name="jerry">  
        <age>5</age>  
        <address>  
            <street>no2street</street>  
            <belongarea>us</belongarea>  
        </address>  
    </person>  
</persons>

首先定义address对应的类

public class Address {
    private String street;
    private String belongArea;

    public String getStreet() {
        return street;
    }

    public void setStreet(String street) {
        this.street = street;
    }

    public String getBelongArea() {
        return belongArea;
    }

    public void setBelongArea(String belongArea) {
        this.belongArea = belongArea;
    }

    @Override
    public String toString(){
        return "street:" +this.getStreet() + ",belongarea:" + this.getBelongArea();
    }
}

接着定义creditcard对应的类

public class Creditcard {
    private int code;
    private String pwd;
    private String limit;
    private String bank;

    public void setParam(String limit,String bank){
        this.limit = limit;
        this.bank = bank;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    public String getLimit() {
        return limit;
    }

    public void setLimit(String limit) {
        this.limit = limit;
    }

    public String getBank() {
        return bank;
    }

    public void setBank(String bank) {
        this.bank = bank;
    }

    @Override
    public String toString(){
        return "limit code:" + this.getCode() + ",pwd:" + this.getPwd() + ",limitValue:" + this.getLimit() + ",bank:" + this.getBank();
    }
}

接下来定义person对应的类

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

/** * Created by Administrator on 2016/7/1 0001. */

public class Person {
    private String name;
    private int age;
    private Address address;
    private List<Creditcard> creditcard = new ArrayList<Creditcard>();

    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 Address getAddress() {
        return address;
    }

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

    public List<Creditcard> getCreditcard() {
        return creditcard;
    }

    public void setCreditcard(List<Creditcard> creditcard) {
        this.creditcard = creditcard;
    }

    public void addCreditcard(Creditcard creditcard){
        this.creditcard.add(creditcard);
    }

    @Override
    public String toString(){
        return "name:" + this.getName() + ",age:" + this.getAge() + "naddress:" + this.getAddress() + "ncreditcare:" + this.getCreditcard();
     }

}

最后定义persons对应的类

public class Root {
    private List<Person> person = new ArrayList<Person>();

    public List<Person> getPerson() {
        return person;
    }

    public void setPerson(List<Person> person) {
        this.person = person;
    }

    public void addPerson(Person person){
        this.person.add(person);
    }

    @Override
    public String toString(){
        for(Person person : this.getPerson()){
            System.out.print( "person: " + person + "n");
        }
        return "";
    }
}

需要注意的是，所有的对象都必须是public类型重点内容

然后来写解析文件

import org.apache.commons.digester.Digester;
import org.xml.sax.SAXException;

import java.io.File;
import java.io.IOException;


public class Main {

    public static void main(String[] args) {
        //digester
        Digester digester = new  Digester();
        digester.setValidating(false);

        digester.addObjectCreate("persons",Root.class);
        digester.addObjectCreate("persons/person",Person.class);

        //name
        digester.addSetProperties("persons/person","name","name");
        //age
        digester.addBeanPropertySetter("persons/person/age");

        //address
        digester.addObjectCreate("persons/person/address",Address.class);
        digester.addBeanPropertySetter("persons/person/address/street");
        digester.addBeanPropertySetter("persons/person/address/belongarea","belongArea");
        digester.addSetNext("persons/person/address","setAddress");

        //creditcard
        digester.addObjectCreate("persons/person/creditcard",Creditcard.class);

        digester.addCallMethod("persons/person/creditcard","setParam",2);
        digester.addCallParam("persons/person/creditcard/limit",0);
        digester.addCallParam("persons/person/creditcard/bank",1);

        /*实现跟上面3条语句同样的功能 digester.addBeanPropertySetter("persons/person/creditcard/limit","limit"); digester.addBeanPropertySetter("persons/person/creditcard/bank","bank");*/
        digester.addSetProperties("persons/person/creditcard/limit","code","code");
        digester.addSetProperties("persons/person/creditcard/limit","pwd","pwd");

        digester.addSetNext("persons/person/creditcard","addCreditcard");
        digester.addSetNext("persons/person","addPerson");
        Root root;
        try {
            root = (Root)digester.parse(new File("C:file3.xml"));
            System.out.println(root);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (SAXException e) {
            e.printStackTrace();
        }

    }
}

1、首先生成Digester对象，并且设置不进行dtd校验 2、addObjectCreate方法是解析标签，第一个参数是对应于xml的标签，第二个参数是Java Bean的Class 这个方法会将一个Class放进栈中 3、addSetProperties方法是解析属性，第一个参数是对应xml的标签，第二个参数是属性名，第三个参数是Bean中的变量名。 4、addBeanProperties方法是解析元素，第一个参数是对应元素，第二个参数是Bean中的变量名，当他们相同时，可以省略。 5、addSetNext方法是解析列表，当一个Class解析完，必须调用，参数一是对应标签，参数二有两种情况，如果有相同的列表，则是add方法，如果没有，就是set方法，相当于出栈。 6、addCallMethod方法，是直接显式调用bean中的方法，参数一是对应标签，参数二是bean中方法名，参数三是方法参数个数。当参数三为0时表示，这个方法有一个参数，取值来自这个标签。当参数三不为0时，要通过addCallParam方法指定参数取值。 addCallParam方法有两个参数，参数1是对应元素，参数二是指当前元素的值作为第几个参数传入addCallMethod方法中。 7、parse方法，传入解析的xml文件。