In direct-injection spark-ignition (DISI) engines, the fuel is injected directly into the cylinder, resulting in the spray impingement on the piston and cylinder surfaces. Liquid films formed on the wall surfaces have a significant influence on combustion efficiency and emissions. To get a better understanding of the spray-wall interaction, fuel vaporization, and liquid film formation processes, this work focused on the spray characteristics of a single-hole gasoline injector with a diameter of 0.135 mm. The fuel sprays impinging on a flat wall were measured quantitatively under different injection pressures and different ambient conditions in a constant-volume vessel. The laser absorption-scattering (LAS) method was used to investigate the differences between free and wall-impinging sprays under evaporating conditions. The ratio of fuel vaporization and the vapor phase distribution were discussed. In addition, quantitative measurements of liquid films were made with the refractive index matching (RIM) method under non-evaporating conditions. For the RIM method, the fuel sprays impact on a quartz plate with one side having a uniformly roughened surface. The liquid film can create a locally smoother surface, increasing the light transmittance of the quartz plate. The film thickness is a nonlinear function of the transmission change in scattered light, which can be determined by a careful calibration procedure. The liquid film thickness, distribution, and total mass were investigated. The comparison of the LAS and RIM results provided insights into the effects of injection conditions on the fuel vaporization and liquid film formation processes.