/**
* Copyright © 2012-2013 <a href="https://github.com/thinkgem/jeesite">JeeSite</a> All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
*/
package com.thinkgem.jeesite.common.persistence.proxy;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.binding.BindingException;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.session.SqlSession;
import com.thinkgem.jeesite.common.persistence.Page;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* <p>
* 执行代理类，扩展Mybatis的方式来让其Mapper接口来支持.
* </p>
*
* @author poplar.yfyang
* @version 1.0 2012-05-13 上午10:09
* @since JDK 1.5
*/
public class PaginationMapperMethod {
private final SqlSession sqlSession;
private final Configuration config;
private SqlCommandType type;
private String commandName;
private String commandCountName;
private final Class<?> declaringInterface;
private final Method method;
private Integer rowBoundsIndex;
private Integer paginationIndex;
private final List<String> paramNames;
private final List<Integer> paramPositions;
private boolean hasNamedParameters;
public PaginationMapperMethod(Class<?> declaringInterface, Method method,
SqlSession sqlSession) {
paramNames = new ArrayList<String>();
paramPositions = new ArrayList<Integer>();
this.sqlSession = sqlSession;
this.method = method;
this.config = sqlSession.getConfiguration();
this.declaringInterface = declaringInterface;
this.hasNamedParameters = false;
setupFields();
setupMethodSignature();
setupCommandType();
validateStatement();
}
/**
* 代理执行方法。
*
* @param args 参数信息
* @return 执行结果
*/
@SuppressWarnings("unchecked")
public Object execute(Object[] args) {
final Object param = getParam(args);
Page<Object> page;
RowBounds rowBounds;
if (paginationIndex != null) {
page = (Page<Object>) args[paginationIndex];
rowBounds = new RowBounds(page.getFirstResult(), page.getMaxResults());
} else if (rowBoundsIndex != null) {
rowBounds = (RowBounds) args[rowBoundsIndex];
page = new Page<Object>();
} else {
throw new BindingException("Invalid bound statement (not found rowBounds or pagination in paramenters)");
}
page.setCount(executeForCount(param));
page.setList(executeForList(param, rowBounds));
return page;
}
/**
* 执行总数的方法，调用方法执行计算总数，取得总结果
*
* @param param 参数信息
* @return 查询的总记录数
*/
private long executeForCount(Object param) {
Number result = (Number) sqlSession.selectOne(commandCountName, param);
return result.longValue();
}
/**
* 取得分页的执行结果，返回的是纪录信息
*
* @param param 参数
* @param rowBounds row
* @return 纪录列表
*/
private List<Object> executeForList(Object param, RowBounds rowBounds) {
return sqlSession.selectList(commandName, param, rowBounds);
}
/**
* 取得当前执行的参数信息
*
* @param args 参数
* @return 参数信息
*/
private Object getParam(Object[] args) {
final int paramCount = paramPositions.size();
if (args == null || paramCount == 0) {
return null;
} else if (!hasNamedParameters && paramCount == 1) {
return args[paramPositions.get(0)];
} else {
Map<String, Object> param = new HashMap<String, Object>();
for (int i = 0; i < paramCount; i++) {
param.put(paramNames.get(i), args[paramPositions.get(i)]);
}
return param;
}
}
private void setupMethodSignature() {
final Class<?>[] argTypes = method.getParameterTypes();
for (int i = 0; i < argTypes.length; i++) {
if (Page.class.isAssignableFrom(argTypes[i])) {
paginationIndex = i;
} else if (RowBounds.class.isAssignableFrom(argTypes[i])) {
rowBoundsIndex = i;
} else {
String paramName = String.valueOf(paramPositions.size());
paramName = getParamNameFromAnnotation(i, paramName);
paramNames.add(paramName);
paramPositions.add(i);
}
}
}
private String getParamNameFromAnnotation(int i, String paramName) {
Object[] annotations = method.getParameterAnnotations()[i];
for (Object annotation : annotations) {
if (annotation instanceof Param) {
hasNamedParameters = true;
paramName = ((Param) annotation).value();
}
}
return paramName;
}
/**
* 设置当前的查询总记录数的ID
*/
private void setupFields() {
commandName = declaringInterface.getName() + "." + method.getName();
commandCountName = commandName + "Count"; // 命名约定
}
/**
* 设置当前的参数的类型信息
*/
private void setupCommandType() {
MappedStatement ms = config.getMappedStatement(commandName);
type = ms.getSqlCommandType();
if (type != SqlCommandType.SELECT) {
throw new BindingException("Unsupport execution method for: " + commandName);
}
}
/**
* 验证Statement
*/
private void validateStatement() {
if (!config.hasStatement(commandName)) {
throw new BindingException("Invalid bound statement (not found): " + commandName);
}
if (!config.hasStatement(commandCountName)) {
throw new BindingException("Invalid bound statement (not found): " + commandCountName);
}
}
}