一、编程式事务
1.在执行事务提交或者回滚之前,事务状态不确定时,可以判断一下事务是否已完成,避免重复提交或者回滚出现异常
举例:
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TransactionStatus transactionStatus = platformTransactionManager.getTransaction(transactionDefinition); if (!transactionStatus.isCompleted()) { platformTransactionManager.commit(transactionStatus); } |
2.由于编程式事务不会自动提交或者回滚,我们可以在try-catch之后加一个finally,判断事务未完成时,进行回滚,保证每个事务一定会结束
举例:
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TransactionStatus transactionStatus = platformTransactionManager.getTransaction(transactionDefinition); try { ... ... } catch (Exception ex) { ... ... } finally { if (!transactionStatus.isCompleted()) { platformTransactionManager.rollback(transactionStatus); } } |
二、Stream
1.使用到的数据结构及模拟数据
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import io.swagger.annotations.ApiModelProperty; import lombok.Data; import java.math.BigDecimal; @Data public class Student { @ApiModelProperty (value = "学生ID" ) private String studentId; @ApiModelProperty (value = "学生姓名" ) private String studentName; @ApiModelProperty (value = "学生性别,1-男,2-女" ) private String studentSex; @ApiModelProperty (value = "学生年龄Integer" ) private Integer studentAgeInt; @ApiModelProperty (value = "学生年龄Double" ) private Double studentAgeDou; @ApiModelProperty (value = "学生年龄BigDecimal" ) private BigDecimal studentAgeDec; } |
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// 数据列表 List List<Student> studentList = new ArrayList<>(); Student student = new Student(); student.setStudentId( "20220930000001" ); student.setStudentName( "赵甲" ); student.setStudentSex( "1" ); student.setStudentAgeInt( 11 ); student.setStudentAgeDou( 11.11 ); student.setStudentAgeDec( new BigDecimal( 11.11 )); studentList.add(student); student = new Student(); student.setStudentId( "20220930000002" ); student.setStudentName( "钱乙" ); student.setStudentSex( "2" ); student.setStudentAgeInt( 12 ); student.setStudentAgeDou( 12.12 ); student.setStudentAgeDec( new BigDecimal( 12.12 )); studentList.add(student); student = new Student(); student.setStudentId( "20220930000003" ); student.setStudentName( "孙丙" ); student.setStudentSex( "1" ); student.setStudentAgeInt( 13 ); student.setStudentAgeDou( 13.13 ); student.setStudentAgeDec( new BigDecimal( 13.13 )); studentList.add(student); student = new Student(); student.setStudentId( "20220930000004" ); student.setStudentName( "李丁" ); student.setStudentSex( "2" ); student.setStudentAgeInt( 14 ); student.setStudentAgeDou( 14.14 ); student.setStudentAgeDec( new BigDecimal( 14.14 )); studentList.add(student); student = new Student(); student.setStudentId( "20220930000005" ); student.setStudentName( "周戊" ); student.setStudentSex( "1" ); student.setStudentAgeInt( 15 ); student.setStudentAgeDou( 15.15 ); student.setStudentAgeDec( new BigDecimal( 15.15 )); studentList.add(student); |
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// 数据Map Map<String,Student> studentMap = new HashMap<>( 5 ); Student student = new Student(); student.setStudentId( "20220930000001" ); student.setStudentName( "赵甲" ); student.setStudentSex( "1" ); student.setStudentAgeInt( 11 ); student.setStudentAgeDou( 11.11 ); student.setStudentAgeDec( new BigDecimal( 11.11 )); studentMap.put(student.getStudentId(),student); student = new Student(); student.setStudentId( "20220930000002" ); student.setStudentName( "钱乙" ); student.setStudentSex( "2" ); student.setStudentAgeInt( 12 ); student.setStudentAgeDou( 12.12 ); student.setStudentAgeDec( new BigDecimal( 12.12 )); studentMap.put(student.getStudentId(),student); student = new Student(); student.setStudentId( "20220930000003" ); student.setStudentName( "孙丙" ); student.setStudentSex( "1" ); student.setStudentAgeInt( 13 ); student.setStudentAgeDou( 13.13 ); student.setStudentAgeDec( new BigDecimal( 13.13 )); studentMap.put(student.getStudentId(),student); student = new Student(); student.setStudentId( "20220930000004" ); student.setStudentName( "李丁" ); student.setStudentSex( "2" ); student.setStudentAgeInt( 14 ); student.setStudentAgeDou( 14.14 ); student.setStudentAgeDec( new BigDecimal( 14.14 )); studentMap.put(student.getStudentId(),student); student = new Student(); student.setStudentId( "20220930000005" ); student.setStudentName( "周戊" ); student.setStudentSex( "1" ); student.setStudentAgeInt( 15 ); student.setStudentAgeDou( 15.15 ); student.setStudentAgeDec( new BigDecimal( 15.15 )); studentMap.put(student.getStudentId(),student); |
2.过滤-filter
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// 过滤所有女生 List<Student> studentListT = studentList.stream() .filter(item -> "2" .equals(item.getStudentSex())).collect(Collectors.toList()); // 过滤12岁以上学生(3种数据类型示例) studentListT = studentList.stream().filter(item -> item.getStudentAgeInt() > 12 ).collect(Collectors.toList()); studentListT = studentList.stream().filter(item -> item.getStudentAgeDou() > 12 ).collect(Collectors.toList()); studentListT = studentList.stream() .filter(item -> item.getStudentAgeDec().compareTo( new BigDecimal( 12 )) > 0 ).collect(Collectors.toList()); // 过滤12岁以上男生(2种方法示例) studentListT = studentList.stream().filter(item -> "1" .equals(item.getStudentSex())) .filter(item -> item.getStudentAgeInt() > 12 ).collect(Collectors.toList()); studentListT = studentList.stream() .filter(item -> "1" .equals(item.getStudentSex()) && item.getStudentAgeInt() > 12 ).collect(Collectors.toList()); |
三、Map转对象
最近,研究map与java对象之间的相互转换,总结了5种方法
http://www.tuohang.net/article/2735.html
四、Linux常用命令
1.查看所有java进程
ps -ef | grep java
2.结束某个进程
kill -9 pid
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原文链接:https://blog.csdn.net/weixin_44200996/article/details/127067774