官网 http://commons.apache.org/proper/commons-digester/
依赖jar包
Digester 3.0 + Logging 1.1.1 + BeanUtils 1.8.3
Digester底层采用SAX解析XML文件
这个Digester 是很强大的，tomcat xml 解析就是他，strusts的也是他，
Digester 的实体必须属性必须实现get，set方法，满足bean的要求
digester 首先解析定义规则
xml的层次
classes
classes/student
classes/student/address
<?xml version="1.0" encoding="UTF-8" ?>
<classes name="四年级" description="超级牛逼">
<student name="张三" age="20">
<address streetName="武侯区" streetNumber="223"/>
</student>
<student name="李四" age="18">
<address streetName="青羊区" streetNumber="900"/>
</student>
</classes>public class Classes {
private String name;
private String description;
private ArrayList<Student> students = new ArrayList();
public void addStudents(Student student) {
this.students.add(student);
}
@Override
public String toString() {
return "Classes{" +
"name='" + name + '\'' +
", description='" + description + '\'' +
", students=" + students +
'}';
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
public class Student {
private String name;
private int age;
private 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 Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
@Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", age=" + age +
", address=" + address +
'}';
}
}
public class Address {
private String streetName;
private String streetNumber;
public String getStreetName() {
return streetName;
}
public void setStreetName(String streetName) {
this.streetName = streetName;
}
public String getStreetNumber() {
return streetNumber;
}
public void setStreetNumber(String streetNumber) {
this.streetNumber = streetNumber;
}
@Override
public String toString() {
return "Address{" +
"streetName='" + streetName + '\'' +
", streetNumber='" + streetNumber + '\'' +
'}';
}
}
public class DigesterTest {
public static void main(String[] args) throws Exception {
URL resource = DigesterTest.class.getClassLoader().getResource("com/digester/classes.xml");
Digester digester = new Digester();
digester.addObjectCreate("classes",Classes.class);//创建一个Classes对象
digester.addSetProperties("classes");//把classes节点全把设置到实体上
digester.addObjectCreate("classes/student", Student.class);//创建一个Student对象
digester.addSetProperties("classes/student");//把student节点全把设置到实体上
digester.addSetNext("classes/student","addStudents");//把节点student，调用addStdents 添加到Classes 对象上
digester.addObjectCreate("classes/student/address", Address.class);
digester.addSetProperties("classes/student/address");
digester.addSetNext("classes/student/address","setAddress");
Classes classes = ((Classes) digester.parse(resource));
System.out.println(classes.toString());
}
}
Classes{name='四年级', description='超级牛逼', students=[Student{name='张三', age=20, address=Address{streetName='武侯区', streetNumber='223'}}, Student{name='李四', age=18, address=Address{streetName='青羊区', streetNumber='900'}}]}
public class DigesterTest {
public static void main(String[] args) throws Exception {
URL resource = DigesterTest.class.getClassLoader().getResource("com/digester/classes.xml");
Digester digester = new Digester();
digester.addRuleSet(new RuleSetBase() {
@Override
public void addRuleInstances(Digester digester) {
digester.addObjectCreate("classes",Classes.class);//创建一个Classes对象
digester.addSetProperties("classes");//把classes节点全把设置到实体上
digester.addObjectCreate("classes/student", Student.class);//创建一个Student对象
digester.addSetProperties("classes/student");//把student节点全把设置到实体上
digester.addSetNext("classes/student","addStudents");//把节点student，调用addStdents 添加到Classes 对象上
digester.addObjectCreate("classes/student/address", Address.class);
digester.addSetProperties("classes/student/address");
digester.addSetNext("classes/student/address","setAddress");
}
});
Classes classes = ((Classes) digester.parse(resource));
System.out.println(classes.toString());
}
}
public class DigesterTest {
public static void main(String[] args) throws Exception {
URL resource = DigesterTest.class.getClassLoader().getResource("com/digester/classes.xml");
Digester digester = new Digester();
digester.addRuleSet(new MyRuleSet());
Classes classes = ((Classes) digester.parse(resource));
System.out.println(classes.toString());
}
}
//迪特米原则，知道最少原则
public class MyRuleSet extends RuleSetBase {
@Override
public void addRuleInstances(Digester digester) {
digester.addObjectCreate("classes",Classes.class);//创建一个Classes对象
digester.addSetProperties("classes");//把classes节点全把设置到实体上
digester.addObjectCreate("classes/student", Student.class);//创建一个Student对象
digester.addSetProperties("classes/student");//把student节点全把设置到实体上
digester.addSetNext("classes/student","addStudents");//把节点student，调用addStdents 添加到Classes 对象上
digester.addObjectCreate("classes/student/address", Address.class);
digester.addSetProperties("classes/student/address");
digester.addSetNext("classes/student/address","setAddress");
}
}Digester类用来将XML映射成Java类，简化XML的处理
对象创建
1.addObjectCreate(String rule,Class class)
设置节点与Java对象的映射规则，rule指定节点的筛选规则，class设置映射对象。SAX解析时，遇到rule指定的节节点，会创建一个class实例放入堆栈中。
比如：addObjectCreate(“classes”,Classes.class) 解析遇到classes节点时，会创建一个Classes实例并放入堆栈中。
属性设置
2.addSetProperties(String rule)
设置节点的属性设置规则。当解析遇到符合rule的节点时，根据属性列表中的属性值对，使用Java反射机制使用标准的JavaBean方法设置栈顶对象实例；
比如：digester.addSetProperties(“classes”),解析遇到user节点时，会获取键值对 <classes name="四年级" description="超级牛逼">获得栈顶的Classes对象，设置实例的name、description属性；
3.addBeanPropertySetter(String rule)
该方法的作用及使用方法类似于addSetProperties，只不过它是用rule所指定的标签来调用对象的setter。
父子关系管理
4.addSetNext(String rule,String methodName)
设置当前rule节点与父节点的调用规则，当遇到rule节点时，调用堆栈中的次栈顶元素调用methodName方法。将栈顶元素作为次顶元素指定方法的输入参数。
5.addCallMethod(String rule,String methodName,int paraNumber)
该方法同样设置对象的属性，但更加灵活，不需要对象具有setter
根据rule规则指定的属性，调用对象的methodName方法，paraNumber参数是表示方法需要的参数个数，当paraNumber=0时，可以单独使用，不然需要配合addCallParam方法
6.addCallParam(String rule,int paraIndex,String attributeName)
该方法与addCallMethod配合使用，根据rule指定的标签属性来调用方法
paraIndex表明需要填充的方法形参序号，从0开始，方法由addCallMethdo指定，attributeName指定标签属性名；
7。 addRuleSet(RuleSet ruleSet),添加规则集合
这个Digester，还有很多功能和方法，需要深入了解请到官网上面查询api
