组合实体模式（Composite Entity Pattern）用在 EJB 持久化机制中。一个组合实体是一个 EJB 实体 bean，代表了对象的图解。当更新一个组合实体时，内部依赖对象 beans 会自动更新，因为它们是由 EJB 实体 bean 管理的。
// 依赖对象
public class DependentObject1 {
private String data;
public void setData(String data) {
this.data = data;
}
public String getData() {
return data;
}
}
public class DependentObject2 {
private String data;
public void setData(String data) {
this.data = data;
}
public String getData() {
return data;
}
}
// 粗粒度对象
public class CoarseGrainedObject {
DependentObject1 do1 = new DependentObject1();
DependentObject2 do2 = new DependentObject2();
public void setData(String data1, String data2) {
do1.setData(data1);
do2.setData(data2);
}
public String[] getData() {
return new String[] {do1.getData(), do2.getData()};
}
}
// 组合实体
public class CompositeEntity {
private CoarseGrainedObject cgo = new CoarseGrainedObject();
public void setData(String data1, String data2) {
cgo.setData(data1, data2);
}
public String[] getData() {
return cgo.getData();
}
}
// 客户端
public class Client {
private CompositeEntity compositeEntity = new CompositeEntity();
public void printData() {
for (int i = 0; i < compositeEntity.getData().length; i++) {
System.out.println("Data: " + compositeEntity.getData()[i]);
}
}
public void setData(String data1, String data2) {
compositeEntity.setData(data1, data2);
}
}