拦截器实现分页

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 一、配置mybastis插件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

<plugins>
<plugin interceptor="com.zhiyi.common.mybatis.SearchInterceptor" />
</plugins>

<mappers>
</mappers>
</configuration>

二、mybatis连接器实现

import com.zhiyi.common.dto.PageSearchDto;
import org.apache.ibatis.executor.statement.PreparedStatementHandler;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.plugin.Invocation;
import org.springframework.util.ReflectionUtils;

import java.lang.reflect.Field;
import java.lang.reflect.Type;
import java.util.Properties;

public class SearchInterceptor implements Interceptor {

public Object intercept(Invocation invocation) throws Throwable {
return invocation.proceed();
}

public Object plugin(Object target) {
Type[] interfaces = target.getClass().getGenericInterfaces();
for (Type i : interfaces) {
if (i.equals(StatementHandler.class)) {
StatementHandler statementHandler = (StatementHandler) target;
Field statementField = ReflectionUtils.findField(statementHandler.getClass(), "delegate");
ReflectionUtils.makeAccessible(statementField);
Object fieldInstance = ReflectionUtils.getField(statementField, statementHandler);

Field mappedStatementField = ReflectionUtils.findField(fieldInstance.getClass(), "mappedStatement");
ReflectionUtils.makeAccessible(mappedStatementField);

MappedStatement mappedStatement = (MappedStatement) ReflectionUtils.getField(mappedStatementField, fieldInstance);

if (mappedStatement.getSqlCommandType() == SqlCommandType.SELECT && fieldInstance.getClass().equals(PreparedStatementHandler.class)) {
PreparedStatementHandler preparedStatementHandler = (PreparedStatementHandler) fieldInstance;
BoundSql boundSql = preparedStatementHandler.getBoundSql();
if (boundSql.getParameterObject() != null &&
(boundSql.getParameterObject().getClass().getSuperclass().equals(PageSearchDto.class))
) {
String additionalSql = null;
if (boundSql.getParameterObject().getClass().getSuperclass().equals(PageSearchDto.class)) {
PageSearchDto searchDto = (PageSearchDto) boundSql.getParameterObject();
if (searchDto.getTotalSize() == -1) {
return target;
}
additionalSql = searchDto.getPageableAndSortableSqlString();
}
String originalSql = boundSql.getSql();
Field sqlField = ReflectionUtils.findField(BoundSql.class, "sql");
ReflectionUtils.makeAccessible(sqlField);
ReflectionUtils.setField(sqlField, boundSql, originalSql + additionalSql);
}
return target;
}
}
}
return target;
}

@Override
public void setProperties(Properties properties) {

}

}

三、通过继承类方式实现

/**
* mybatis拦截器 对应分页dto
*/
public class PageSearchDto extends SearchDto {

//每页记录数
protected int pageSize = 20;

//当前第几页
protected int currentPage = 1;

//总记录数
protected int totalSize;

//总页数
protected int totalPage;

//排序字段
protected List<String> sortColumn = new ArrayList<String>();

protected List<String> sortDirection = new ArrayList<String>();

public int getTotalPage() {
return totalPage;
}

public void setTotalPage(int totalPage) {
this.totalPage = totalPage;
}

public int getPageSize() {
return pageSize;
}

public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}

public int getCurrentPage() {
return currentPage;
}

public void setCurrentPage(int currentPage) {
this.currentPage = currentPage;
}

public List<String> getSortColumn() {
return sortColumn;
}

public void setSortColumn(List<String> sortColumn) {
this.sortColumn = sortColumn;
}

public List<String> getSortDirection() {
return sortDirection;
}

public int getTotalSize() {
return totalSize;
}

public void setTotalSize(int totalSize) {
this.totalSize = totalSize;
}

public void setSortDirection(List<String> sortDirection) {
this.sortDirection = sortDirection;
}

public void addSortCriteria(String property, String direction) {
getSortColumn().add(property);
getSortDirection().add(direction);
}

protected String getSortableSql() {
if (getSortColumn().size() == 0) {
return "";
}
StringBuilder stringBuilder = new StringBuilder(" order by ");
for (int i = 0; i < sortColumn.size(); i++) {
stringBuilder.append(sortColumn.get(i)).append(" " + sortDirection.get(i) + ", ");
}
return stringBuilder.substring(0, stringBuilder.length() - 2);
}

protected String getPageableSql() {
StringBuilder stringBuilder = new StringBuilder("");
if (currentPage <= 1 && pageSize != -1) {
stringBuilder.append("limit ").append("0," + pageSize);
} else if (currentPage > 1) {
int start = (currentPage - 1) * pageSize;
stringBuilder.append("limit ").append(start + "," + pageSize);
}

return stringBuilder.toString();
}

public void clearSort() {
if (null != sortColumn) {
sortColumn.clear();
}
if (null != sortDirection) {
sortDirection.clear();
}
}

public void resetPagination(int currentPage, int pageSize, String property, String direction) {
this.clearSort();
this.setCurrentPage(currentPage);
this.setPageSize(pageSize);
if (StringUtils.isNotBlank(property) || StringUtils.isNotBlank(direction)) {
this.addSortCriteria(property, direction);
}
}

public String getPageableAndSortableSqlString() {
return getSortableSql() + " " + getPageableSql();
}

public int calTotalPage(int totalSize) {
this.totalSize = totalSize;
int page = totalSize / pageSize;
this.totalPage = (totalSize % pageSize) == 0 ? page : page + 1;
return totalPage;
}

//设置不分页
public Object disablePaging() {
this.setTotalSize(-1);
return this;
}

public Object openPaging() {
this.setTotalSize(0);
return this;
}
}

四、使用demo

List<AdminSection> adminSections = adminSectionMapper.search(sectionSearchDto);
List<AdminSectionDto> adminSectionDtos = PropertiesUtils.copyList(AdminSectionDto.class, adminSections);
return new PageSearchResultDto<>(this.count(sectionSearchDto), adminSectionDtos);