享元模式

public interface QueryManager {
    
    public String createQuery();
    
    public void setStatus(String status);
}

public class EmployeeQueryManager implements QueryManager {

    protected String name;          //内部状态
    
    public EmployeeQueryManager(String name){
        this.name = name;
    }
    
    @Override
    public String createQuery() {
        return "This is EmployeeQuery : "+name;
    }

    @Override
    public void setStatus(String status) {
        System.out.println("Employee Status : " + status);      //外部状态
    }

}

public class CompanyQueryManager implements QueryManager {

    protected String name;              //内部状态
    
    public CompanyQueryManager(String name){
        this.name = name;
    }
    
    @Override
    public String createQuery() {
        return "This is CompanyQuery : " + name;
    }

    @Override
    public void setStatus(String status) {
        System.out.println("Company Status : " + status);       //外部状态
    }
}

public class QueryManagerFactory {
    
    static Map<String,QueryManager> eqm = new HashMap<String,QueryManager>();
    static Map<String,QueryManager> cqm = new HashMap<String,QueryManager>();
    
    
    public QueryManager getCompanyQueryManager(String name){
        QueryManager qm = cqm .get(name);
        if(qm==null){
            qm = new CompanyQueryManager(name);
            cqm.put(name, qm);
        }
        return qm;
    }
    
    public QueryManager getEmployeeQueryManager(String name){
        QueryManager qm = eqm .get(name);
        if(qm==null){
            qm = new EmployeeQueryManager(name);
            eqm.put(name, qm);
        }
        return qm;
    }
    
    public static int getCompanySize(){
        return cqm.size();
    }
    
    public static int getEmployeeSize(){
        return eqm.size();
    }
}

public class FlyWeightTest {
    
    public static void main(String[] args) {
        QueryManagerFactory qmf = new QueryManagerFactory();
        QueryManager qma = qmf.getCompanyQueryManager("公司甲");
        qma.setStatus("false");                                     //Company Status : false
        QueryManager qm1 = qmf.getEmployeeQueryManager("员工甲");
        qm1.setStatus("true");                                      //Employee Status : true
        QueryManager qm2 = qmf.getEmployeeQueryManager("员工乙");
        qm2.setStatus("false");                                     //Employee Status : false
        QueryManager qm3 = qmf.getEmployeeQueryManager("员工甲");
        qm3.setStatus("false");                                     //Employee Status : false
        System.out.println(qma.createQuery() + "; CompanyQuery size : " + qmf.getCompanySize());    
        //This is CompanyQuery : 公司甲; CompanyQuery size : 1
        System.out.println(qm1.createQuery() + "; EmployeeQuery size : " + qmf.getEmployeeSize());
        //This is EmployeeQuery : 员工甲; EmployeeQuery size : 2
        System.out.println(qm2.createQuery() + "; EmployeeQuery size : " + qmf.getEmployeeSize());
        //This is EmployeeQuery : 员工乙; EmployeeQuery size : 2
        System.out.println(qm3.createQuery() + "; EmployeeQuery size : " + qmf.getEmployeeSize());
        //This is EmployeeQuery : 员工甲; EmployeeQuery size : 2
    }
}