图3 |
图4 |
2、我的这个SessionBean要实现客户端程序和数据库的接口。也就是说所有的SQL语句可以通过这个SessionBean来执行并返回处理结果。
首先定义了一个SQL语句类的接口
package hello;
public interface DefaultSQLContext {
public String getSQL();
public String[] getParameterType();
public int getType();
} |
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所有的封装了SQL语句的类都必须要实现该接口。
例如：hello.TestSQL.java
package hello;
public class TestSQL implements DefaultSQLContext{
static String[] paraValue;
public String getSQL(){
return "select baseitemid,datasource,baseitemname,maxlength,description from ctm_baseitem where businesstypeid=?";
}
public String[] getParameterType(){
return new String[]{"varchar"};
}
//执行SQL的动作类型，是查询还是更新语句；
//0是查询语句，1表示更新语句；
public int getType(){
return 0;
}
} |
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EJB的程序如下所示：
hello.HelloWord.java文件如下所示：
package hello;
import java.rmi.*;
import javax.ejb.*;
import java.sql.*;
import java.util.Vector;
public interface HelloWorld extends EJBObject {
public void execute() throws RemoteException;
public Vector getQueryResult() throws RemoteException;
} |
提供了执行SQL语句的execute()方法，getQueryResult()方法获得查询获得值。
Hello. HelloWorldBean文件如下所示，真正的执行程序：
package hello;
import java.rmi.*;
import javax.ejb.*;
import javax.sql.*;
import javax.naming.*;
import java.util.*;
import java.sql.*;
public class HelloWorldBean implements SessionBean {
private SessionContext sessionContext;
private defaultSQLContext sql;
private String sqlContext = "";
private Connection con = null;
private Context initCtx = null;
private Vector vResult,vColumnName;
private int iReturn = 1;
String[] paraValue;
public void init(){
try{
initCtx= new InitialContext();
DataSource ds = (javax.sql.DataSource) initCtx.lookup("DBSource");
con= ds.getConnection();
System.out.println("connection = "+con);
}catch(Exception e){System.out.println(e);}
}
/*
//设置SQLContext的类名；
public void setSqlContext(String str){
sqlContext = str;
}
*/
private void initSQLContext(){
init();
try{
Class aclass= Class.forName(sqlContext);
sql = (defaultSQLContext)aclass.newInstance();
}catch (Exception e){
System.out.println("cannot initialize instance"+sqlContext);
System.out.println(e);
}
}
/*
public void setParaValue(String[] str){
this.paraValue = str;
}
*/
public void execute(){
String[] paraType;
int iColumnCount = 0;
ResultSet rs = null;
ResultSetMetaData rsm= null;
Vector vInnerValue;
//首先获得SQLContext;
initSQLContext();
try{
PreparedStatement ps = con.prepareStatement(sql.getSQL());
System.out.println("SQL = "+sql.getSQL());
if(sql.getParameterType()!=null&¶Value!=null)
{
paraType = sql.getParameterType();
for(int i=0;i {
if(paraType[i].equalsIgnoreCase("varchar")||paraType[i].equalsIgnoreCase("varchar2"))
ps.setString(i+1,paraValue[i].trim());
else if(paraType[i].equalsIgnoreCase("integer")||paraType[i].equalsIgnoreCase("int"))
ps.setInt(i+1,Integer.parseInt(paraValue[i].trim()));
else if(paraType[i].equalsIgnoreCase("long"))
ps.setLong(i+1,Long.parseLong(paraValue[i].trim()));
else if(paraType[i].equalsIgnoreCase("date"))
ps.setDate(i+1,java.sql.Date.valueOf(paraValue[i].trim()));
else if(paraType[i].equalsIgnoreCase("boolean"))
ps.setBoolean(i+1,Boolean.getBoolean(paraValue[i].trim()));
else if(paraType[i].equalsIgnoreCase("double"))
ps.setDouble(i+1,Double.parseDouble(paraValue[i].trim()));
else
ps.setString(i+1,paraValue[i].trim());
System.out.print("ParameterType["+i+"] = "+paraType[i]);
System.out.println(" ParameterValue["+i+"] = "+paraValue[i]);
}//end for
}//end if
if(sql.getType()==0) //查询；
{
vResult = new Vector();
System.out.println("execute Query!");
rs = ps.executeQuery();
rsm= rs.getMetaData();
iColumnCount= rsm.getColumnCount();
while(rs.next()){
vInnerValue= new Vector();
for(int j=1;j<=iColumnCount;j++)
{
Object o = rs.getObject(j);
if(o==null)
vInnerValue.addElement("");
else
vInnerValue.addElement(o.toString());
}//end for
vResult.addElement(vInnerValue);
}//end while
vColumnName = new Vector(); //获得字段名；
for(int i=1;i<=iColumnCount;i++)
vColumnName.addElement(rsm.getColumnName(i));
}//end if 查询；
else if(sql.getType()==1) //更新语句；
{
try{
System.out.println("execute Update!");
iReturn = ps.executeUpdate();
con.commit();
}catch(Exception ex)
{
iReturn=0;
con.rollback();
System.out.println("update ejb error!"+ex);
}
}
ps.close();
}catch (Exception ne){
System.out.println(ne);
}
}
public Vector getQueryResult(){
return vResult;
}
public Vector getColumnName(){
return vColumnName;
}
public int getUpdateResult(){
return iReturn;
}
/*
public void ejbCreate(){
System.out.println("ejbCreate()");
}
public void ejbCreate(String sqlContext){
ejbCreate(sqlContext,null);
System.out.println("ejbCreate()");
}
*/
public void ejbCreate(String sqlContext,String[] paraValue) {
this.sqlContext = sqlContext;
this.paraValue = paraValue;
System.out.println("ejbCreate()");
}
public void ejbRemove() {
}
public void ejbActivate() {
}
public void ejbPassivate() {
}
public void setSessionContext(SessionContext context) {
sessionContext = context;
}
}
hello. HelloWorldHome文件（定义Home接口）如下所示：
package hello;
import java.rmi.*;
import javax.ejb.*;
public interface HelloWorldHome extends EJBHome{
public HelloWorld create(String sqlContext,String[] paraValue) throws RemoteException, CreateException;
}
客户端测试程序：
package hello;
import javax.naming.*;
import javax.rmi.PortableRemoteObject;
import java.util.*;
import java.sql.*;
public class HelloWorldBeanClient1 {
private static HelloWorldHome helloWorldHome = null;
private static HelloWorld hello = null;
static{
Context ctx = null;
Hashtable ht = new Hashtable();
System.out.println("Initializing bean access.");
try{
ht.put(Context.INITIAL_CONTEXT_FACTORY,"weblogic.jndi.WLInitialContextFactory");
ht.put(Context.PROVIDER_URL,"t3://localhost:7001");
ctx = new InitialContext(ht);
//look up jndi name
Object ref = ctx.lookup("testBean");
//cast to Home interface
helloWorldHome = (HelloWorldHome) PortableRemoteObject.narrow(ref, HelloWorldHome.class);
System.out.println("Get the ejbHome.");
String[] paraValue = new String[]{"16"};
hello=helloWorldHome.create("hello.testSQL",paraValue);
}catch(Exception e){System.out.println("cannot get the ejbBean!"+e);}
}
public HelloWorldBeanClient1() {
Vector vInnerValue;
try {
//hello.setParaValue(value);
//hello.setSqlContext("hello.testSQL");
hello.execute();
Vector columnName = hello.getColumnName();
Vector result = hello.getQueryResult();
for(int i=0;i {
vInnerValue = (Vector)result.elementAt(i);
for(int j=0;j {
System.out.print(columnName.elementAt(j)+" = ");
System.out.println(vInnerValue.elementAt(j));
}
}
//System.out.println("execute Result = "+hello.getUpdateResult());
}catch(Exception e) {
System.out.println("Failed initializing bean access.");
e.printStackTrace();
}
}
/**Main method*/
public static void main(String[] args) {
HelloWorldBeanClient1 client = new HelloWorldBeanClient1();
}
}
} |
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