利用Digester實現xml和bean之間的轉換（二）
阿新 • • 發佈：2019-02-16
Digester框架屬於Jakarta Commons，它以規則和模式為基礎處理XML文件。與SAX和DOM之類的標準API相比，Digester不涉及太多的細節問題，非常適合於對XML文件進行簡單的處理。
比如要解析如下的xml檔案
<persons>
<person name="tom">
<age>4</age>
<address>
<street>no1street</street>
<belongarea 首先定義address對應的類
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();
}
}
接著定義creditcard對應的類
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();
}
}接下來定義person對應的類
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();
}
}最後定義persons對應的類
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，所有的物件都必須是public型別重點內容
然後來寫解析檔案
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);
/*實現跟上面3條語句同樣的功能
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物件，並且設定不進行dtd校驗
2、addObjectCreate方法是解析標籤，第一個引數是對應於xml的標籤，第二個引數是Java Bean的Class
這個方法會將一個Class放進棧中
3、addSetProperties方法是解析屬性，第一個引數是對應xml的標籤，第二個引數是屬性名，第三個引數是Bean中的變數名。
4、addBeanProperties方法是解析元素，第一個引數是對應元素，第二個引數是Bean中的變數名，當他們相同時，可以省略。
5、addSetNext方法是解析列表，當一個Class解析完，必須呼叫，引數一是對應標籤，引數二有兩種情況，如果有相同的列表，則是add方法，如果沒有，就是set方法，相當於出棧。
6、addCallMethod方法，是直接顯式呼叫bean中的方法，引數一是對應標籤，引數二是bean中方法名，引數三是方法引數個數。當引數三為0時表示，這個方法有一個引數，取值來自這個標籤。當引數三不為0時，要通過addCallParam方法指定引數取值。
addCallParam方法有兩個引數，引數1是對應元素，引數二是指當前元素的值作為第幾個引數傳入addCallMethod方法中。
7、parse方法，傳入解析的xml檔案。