NSLog日志输出不全问题分析与解决方案

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拔山河 2022-08-19 02:40:20 博主文章分类：日志 ©著作权

文章标签 NSLog打印日志被截断问题字符串拼接打印含有汉字的字符串拼接打印超过1021个字符的字符串打印不完全先拼接字符串后打印字符串 文章分类 代码人生

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采用NSLog打印超长的字符串，可能出现日志没有打印完全，后面一部分丢失了。
开始以为是和异步一致一起打印时被异步日志线程强行插入，结果找了半天没有找到，说明它根本没有打印出来。
出问题的日志打印代码：NSLog(@"3加密前：%@", data);，怎么看这个代码没有任何问题，打印（NSLog(@"data.length:%d", data.length);）出的这个字符串长度是比较长：data.length:7353。我怀疑是系统这个打印函数是有内存限制，超过它的长度就直接截取扔掉了后面的字符。
分析它最大能支持多长的字符串：加[ { "openType" : "03", "openTime" : "1564651163", "uid" : "3130303030393539" }, { "openType" : "03", "openTime" : "1564651170", "uid" : "3130303030393539" }, { "openType" : "03", "openTime" : "1564651176", "uid" : "3130303030393539" }, { "openType" : "03", "openTime" : "1564651182", "uid" : "3130303030393539" }, { "openType" : "03", "openTime" : "1564651188", "uid" : "3130303030393539" }, { "openType" : "03", "openTime" : "1564651194", "uid" : "3130303030393539" }, { "openType" : "03", "openTime" : "1564651200", "uid" : "3130303030393539" }, { "openType" : "03", "openTime" : "1564651206", "uid" : "3130303030393539" }, { "openType" : "03", "openTime" : "1564651212", "uid" : "3130303030393539" }, { "openType" : "03", "openTime" : "1564651218", "uid" : "3130303030393539" }, { "openType" : "03", "ope，它实际只有1021个包含空格汉字的字符。难道它真的只能打印这么一点字符串吗？
我直接对这个字符串打印：NSLog(@"%@", data);。结果直接把这7353个字符全部打印出来了。可以看到它不是只打印这1021个汉字和字符这么点内容，应该可以打印很多。
难道是因为拼接的同时进行打印才有这个限制，我测试这种情况：NSLog(@"testdata%@", data);，结果仍是可以把这7353个字符全部打印出来。可以看出推测不完全对。
然后我试一下再外面拼接字符串，直接对字符串进行打印：

                str = [NSString stringWithFormat:@"加%@", data];
                NSLog(@"%@", str);

结果和不行，也把这7353个字符全部打印出来。可以看出推测不完全对。
比对他们的不同发现了规律：在打印是拼接字符串，并且里面的常量字符串里有中文，才会出现打印的字符串很短，超过最大的长度字符串后面的部分被扔掉。那么找到的问题的所在，那来研究下这个最大长度是多少呢？
由于发现打印的最大的字符串最大是1021个字符，包含一个汉字，很可能和1021个字符有关，就对字符串进行截取测试。测试发现：在一个中文常量的情况下，和一个1020个字符的字符串拼接没有问题，但是和1021个字符的字符串拼接后打印少了最后一个字符。
总结：
当直接打印一个长字符串，只要不是超级长，一般没有问题。当加入输出信息，并且有常量中文时，和变量字符串拼接时，当他们的字符数和超过1021时，后面的字符串打印不出来（测试的场景是：一个中文字符和和不含有非汉字json字符串。若中文多，他们的总和是否为1021，没有进一步研究）。
开发环境有效的重置NSLog的方法，这种方案我提倡，这个已经原来的mac的控制台打印函数，而是采用的linux操作系统日志函数进行替换了原来的函数了：

#ifndef __OPTIMIZE__
    //这里执行的是debug模式下，打印日志，当前行
    #define NSLog(...) printf("%s %s 第%d行: %s\n",__TIME__, __PRETTY_FUNCTION__ ,__LINE__, [[NSString stringWithFormat:__VA_ARGS__] UTF8String]);
#else
        //这里执行的是release模式下，不打印日志
    #define NSLog(...)
#endif

推荐解决方案：
先把要打印的所有字符串拼接为一个字符串，然后一次打印。

解决方案：
先把要打印的所有字符串拼接为一个字符串，然后一次打印。至于直接重置NSLog：#define NSLog(format, ...) printf("TIME:%s FILE:%s(%d行) FUNCTION:%s \n %s\n\n",__TIME__, [[[NSString stringWithUTF8String:__FILE__] lastPathComponent] UTF8String], __LINE__, __PRETTY_FUNCTION__, [[NSString stringWithFormat:(format), ##__VA_ARGS__] UTF8String])我不提倡。
测试代码：

                NSLog(@"data.length:%d", data.length);
                NSString *str = [NSString stringWithFormat:@"%@", [data substringToIndex:1022]];
                NSLog(@"加%@", str);
                NSLog(@"str.length:%d", str.length);
                str = [NSString stringWithFormat:@"%@", [data substringToIndex:1021]];
                NSLog(@"加%@", str);
                str = [NSString stringWithFormat:@"加%@", [data substringToIndex:1021]];
                NSLog(@"%@", str);
                NSLog(@"str.length:%d", str.length);
                str = [NSString stringWithFormat:@"%@", [data substringToIndex:1020]];
                NSLog(@"加%@", str);
                str = [NSString stringWithFormat:@"加%@", [data substringToIndex:1020]];
                NSLog(@"%@", str);
                NSLog(@"str.length:%d", str.length);
//                str = [NSString stringWithFormat:@"3加密前：data:%@", data];
                NSLog(@"3加密前：%@", data);

打印的日志，大家可以对照进行分析：

2019-08-02 16:11:54.297359+0800 ELock[1447:400407] data.length:7353
2019-08-02 16:11:54.297597+0800 ELock[1447:400407] 加[    {       "openType" : "03",      "openTime" : "1564651163",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "openTime" : "1564651170",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "openTime" : "1564651176",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "openTime" : "1564651182",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "openTime" : "1564651188",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "openTime" : "1564651194",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "openTime" : "1564651200",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "openTime" : "1564651206",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "openTime" : "1564651212",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "openTime" : "1564651218",      "uid" : "3130303030393539"   },     {       "openType" : "03",      "ope
2019-08-02 16:11:54.461804+0800 ELock[1447:400407] str.length:1022
2019-08-02 16:11:54.461982+0800 ELock[1447:400407] 加[    {       "openType" : "03",      "openTime" : "1564651163",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651170",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651176",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651182",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651188",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651194",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651200",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651206",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651212",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651218",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "ope
2019-08-02 16:11:54.473584+0800 ELock[1447:400407] 加[    {       "openType" : "03",      "openTime" : "1564651163",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651170",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651176",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651182",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651188",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651194",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651200",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651206",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651212",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651218",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "open
2019-08-02 16:11:54.475564+0800 ELock[1447:400407] str.length:1022
2019-08-02 16:11:54.475860+0800 ELock[1447:400407] 加[    {       "openType" : "03",      "openTime" : "1564651163",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651170",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651176",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651182",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651188",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651194",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651200",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651206",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651212",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651218",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "ope
2019-08-02 16:11:54.477939+0800 ELock[1447:400407] 加[    {       "openType" : "03",      "openTime" : "1564651163",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651170",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651176",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651182",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651188",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651194",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651200",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651206",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651212",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "openTime" : "1564651218",      "uid" : "3420303038763539"   },     {       "openType" : "03",      "ope
2019-08-02 16:11:54.480312+0800 ELock[1447:400407] str.length:1021