README.md
1## Send Rust logs to Logcat
2
3[](https://crates.io/crates/android_logger)
4[](https://github.com/Nercury/android_logger-rs/actions/workflows/ci.yml/)
5
6
7This library is a drop-in replacement for `env_logger`. Instead, it outputs messages to
8android's logcat.
9
10This only works on Android and requires linking to `log` which
11is only available under android. With Cargo, it is possible to conditionally require
12this library:
13
14```toml
15[target.'cfg(target_os = "android")'.dependencies]
16android_logger = "0.11"
17```
18
19Example of initialization on activity creation, with log configuration:
20
21```rust
22#[macro_use] extern crate log;
23extern crate android_logger;
24
25use log::LevelFilter;
26use android_logger::{Config,FilterBuilder};
27
28fn native_activity_create() {
29 android_logger::init_once(
30 Config::default()
31 .with_max_level(LevelFilter::Trace) // limit log level
32 .with_tag("mytag") // logs will show under mytag tag
33 .with_filter( // configure messages for specific crate
34 FilterBuilder::new()
35 .parse("debug,hello::crate=error")
36 .build())
37 );
38
39 trace!("this is a verbose {}", "message");
40 error!("this is printed by default");
41}
42```
43
44To allow all logs, use the default configuration with min level Trace:
45
46```rust
47#[macro_use] extern crate log;
48extern crate android_logger;
49
50use log::LevelFilter;
51use android_logger::Config;
52
53fn native_activity_create() {
54 android_logger::init_once(
55 Config::default().with_max_level(LevelFilter::Trace),
56 );
57}
58```
59
60There is a caveat that this library can only be initialized once
61(hence the `init_once` function name). However, Android native activity can be
62re-created every time the screen is rotated, resulting in multiple initialization calls.
63Therefore this library will only log a warning for subsequent `init_once` calls.
64
65This library ensures that logged messages do not overflow Android log message limits
66by efficiently splitting messages into chunks.
67
68## License
69
70Licensed under either of
71
72 * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
73 * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
74
75at your option.
76
77### Contribution
78
79Unless you explicitly state otherwise, any contribution intentionally
80submitted for inclusion in the work by you, as defined in the Apache-2.0
81license, shall be dual licensed as above, without any additional terms or
82conditions.
83
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