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。