Java return file content

The same results can be achieved by invoking the lines method on BufferedReader also. Here is an example:. As streams are lazy-loaded in the above cases i.

The Files. It is possible to create a stream from this collection, by invoking the stream method on it:. However, this method loads the entire contents of the file in one go and hence is not memory efficient like the Files. The try-with-resources syntax provides an exception handling mechanism that allows us to declare resources to be used within a Java try-with-resources block.

When the execution leaves the try-with-resources block, the used resources are automatically closed in the correct order whether the method successfully completes or any exceptions are thrown. We can use try-with-resources to close any resource that implements either AutoCloseable or Closeable. Streams are AutoCloseable implementations and need to be closed if they are backed by files. By default, streams are serial, meaning that each step of a process is executed one after the other sequentially.

Streams can be easily parallelized, however. This means that a source stream can be split into multiple sub-streams executing in parallel. Each substream is processed independently in a separate thread and finally merged to produce the final result.

You can see that the stream elements are printed in random order. This is because the order of the elements is not maintained when forEach is executed in the case of parallel streams.

Parallel streams may perform better only if there is a large set of data to process. In other cases, the overhead might be more than that for serial streams.

Hence, it is advisable to go for proper performance benchmarking before considering parallel streams. All the methods we saw until now have overloaded versions that take a specified charset also as an argument. Like Files. Java 8 also introduced BufferedReader. This is demonstrated below using Stream:. BufferedReader ; import java. FileReader ; import java. Java 11 introduced the Files. It takes a path to the file and overloaded to accept the charset used for decoding from bytes to characters.

Several third-party libraries provide utility methods for working with files. Guava provides the Files. Charsets ; import com. For an ImmutableList , use Files. Note that both these methods strip line-termination characters from the end of each line. Joiner ; import com. Like Guava library, Apache Commons IO FileUtils class provides the readFileToString method that allows you to read the contents of any file into a string using the specified charset for converting Bytes from the file into characters.

FileUtils ; import java. It takes an InputStream and renders its contents as a String, as shown below:. IOUtils ; import java. FileInputStream ; import java. We can also construct a Scanner that produces values scanned from the specified file. This is demonstrated below using the try-with-resources block to automatically takes care of scanner. Compare two file paths. Match a path which may contain a wildcard.

Merges the two paths to create a valid version of the second path. Return the page type extracting it from the path. Display directory tree. Get file separator using System class. Remove file information from a filename returning only its path component. Remove path information from a filename returning only its file component. Strip a filename of its last extension the portion immediately following the last dot character, if any.

Remove path and file information from a filename returning only its extension component. In this episode find out how to return a file from a spring controller. In this example we will show how to read a PDF from the classpath simulating a read from a database or a file system and downloading it from a RESTful web service.

While we use a PDF you could substitute just about any file format such as gif, jpeg, tiff, png, zip, jars, wars, ear or any other binary format that you need to stream to your browser.

More examples show how to make a get request for json and return xml from a spring rest service.