/**
* 对象中获取分页参数
*
* @param params
* @return
*/
public static Page getPageFromObject(Object params) {
int pageNum;
int pageSize;
MetaObject paramsObject = null;
if (params == null) {
throw new NullPointerException("分页查询参数params不能为空!");
}
if (hasRequest && requestClass.isAssignableFrom(params.getClass())) {
try {
paramsObject = SystemMetaObject.forObject(getParameterMap.invoke(params, new Object[] {}));
} catch (Exception e) {
// 忽略
}
} else {
paramsObject = SystemMetaObject.forObject(params);
}
if (paramsObject == null) {
throw new NullPointerException("分页查询参数params处理失败!");
}
try {
pageNum = Integer.parseInt(String.valueOf(getParamValue(paramsObject, "pageNum", true)));
pageSize = Integer.parseInt(String.valueOf(getParamValue(paramsObject, "pageSize", true)));
} catch (NumberFormatException e) {
throw new IllegalArgumentException("分页参数不是合法的数字类型!");
}
Object _count = getParamValue(paramsObject, "count", false);
boolean count = true;
if (_count != null) {
count = Boolean.valueOf(String.valueOf(_count));
}
Page page = new Page(pageNum, pageSize, count);
Object reasonable = getParamValue(paramsObject, "reasonable", false);
if (reasonable != null) {
page.setReasonable(Boolean.valueOf(String.valueOf(reasonable)));
}
Object pageSizeZero = getParamValue(paramsObject, "pageSizeZero", false);
if (pageSizeZero != null) {
page.setPageSizeZero(Boolean.valueOf(String.valueOf(pageSizeZero)));
}
return page;
}
/**
* 获取分页参数
*
* @param params RowBounds参数
* @return 返回Page对象
*/
public Page getPage(Object params) {
Page page = getLocalPage();
if (page == null) {
if (params instanceof RowBounds) {
RowBounds rowBounds = (RowBounds) params;
if (offsetAsPageNum) {
page = new Page(rowBounds.getOffset(), rowBounds.getLimit(), rowBoundsWithCount);
} else {
page = new Page(rowBounds, rowBoundsWithCount);
// offsetAsPageNum=false的时候，由于PageNum问题，不能使用reasonable，这里会强制为false
page.setReasonable(false);
}
} else {
page = getPageFromObject(params);
}
setLocalPage(page);
}
// 分页合理化
if (page.getReasonable() == null) {
page.setReasonable(reasonable);
}
// 当设置为true的时候，如果pagesize设置为0（或RowBounds的limit=0），就不执行分页，返回全部结果
if (page.getPageSizeZero() == null) {
page.setPageSizeZero(pageSizeZero);
}
return page;
}
/**
* Mybatis拦截器方法
*
* @param invocation 拦截器入参
* @return 返回执行结果
* @throws Throwable 抛出异常
*/
private Object _processPage(Invocation invocation) throws Throwable {
final Object[] args = invocation.getArgs();
RowBounds rowBounds = (RowBounds) args[2];
if (SqlUtil.getLocalPage() == null && rowBounds == RowBounds.DEFAULT) {
if (OrderByHelper.getOrderBy() != null) {
OrderByHelper.processIntercept(invocation);
}
return invocation.proceed();
} else {
// 获取原始的ms
MappedStatement ms = (MappedStatement) args[0];
// 判断并处理为PageSqlSource
if (!isPageSqlSource(ms)) {
processMappedStatement(ms, parser);
}
// 忽略RowBounds-否则会进行Mybatis自带的内存分页
args[2] = RowBounds.DEFAULT;
// 分页信息
Page page = getPage(rowBounds);
// pageSizeZero的判断
if ((page.getPageSizeZero() != null && page.getPageSizeZero()) && page.getPageSize() == 0) {
COUNT.set(null);
// 执行正常（不分页）查询
Object result = invocation.proceed();
// 得到处理结果
page.addAll((List) result);
// 相当于查询第一页
page.setPageNum(1);
// 这种情况相当于pageSize=total
page.setPageSize(page.size());
// 仍然要设置total
page.setTotal(page.size());
// 返回结果仍然为Page类型 - 便于后面对接收类型的统一处理
return page;
}
// 简单的通过total的值来判断是否进行count查询
if (page.isCount()) {
COUNT.set(Boolean.TRUE);
// 替换MS
args[0] = msCountMap.get(ms.getId());
// 查询总数
Object result = invocation.proceed();
// 还原ms
args[0] = ms;
// 设置总数
page.setTotal((Integer) ((List) result).get(0));
if (page.getTotal() == 0) {
return page;
}
}
// pageSize>0的时候执行分页查询，pageSize<=0的时候不执行相当于可能只返回了一个count
if (page.getPageSize() > 0
&& ((rowBounds == RowBounds.DEFAULT && page.getPageNum() > 0)
|| rowBounds != RowBounds.DEFAULT)) {
// 将参数中的MappedStatement替换为新的qs
COUNT.set(null);
BoundSql boundSql = ms.getBoundSql(args[1]);
args[1] = parser.setPageParameter(ms, args[1], boundSql, page);
COUNT.set(Boolean.FALSE);
// 执行分页查询
Object result = invocation.proceed();
// 得到处理结果
page.addAll((List) result);
}
// 返回结果
return page;
}
}